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Black hole feedback in the luminous quasar PDS 456
Abstract
The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spherical stream of highly ionized gas in the broadband x-ray spectra of the luminous quasar PDS 456. This persistent wind is expelled at relativistic speeds from the inner accretion disk, and its wide aperture suggests an effective coupling with the ambient gas. The outflow's kinetic power larger than 10(46) ergs per second is enough to provide the feedback required by models of black hole and host galaxy coevolution.
Copyright © 2015, American Association for the Advancement of Science.
... While in many cases significant flux variations can be attributed to variations in the line-of-sight absorbers (e.g., NGC 1365; Risaliti et al. 2005;Walton et al. 2014), some sources have been also observed to vary dramatically in the X-ray intrinsic flux. Recent long XMM-Newton and NuSTAR observations of highly variable sources have led to a number of results that shed light on the accretion/ejection mechanisms in their innermost regions, such as PDS 456 (Nardini et al. 2015;Reeves et al. 2018), IRAS 13349+2438 , IRAS 13224-3809 (Parker et al. 2017), MCG 03-58-007 (Braito et al. 2021) and NGC 3783 (Costanzo et al. 2022), among others. ...
... Equation (4) is calculated under the assumption of a spherical symmetric flow (Crenshaw et al. 2003;Crenshaw & Kraemer 2012), as commonly assumed for UFOs (see e.g., Tombesi et al. 2012;Nardini et al. 2015;Fiore et al. 2017;Chartas et al. 2021). However, the outflow in NGC 2992 shows a very low duty cycle and a short-term variation of its spectral appearance, equal to or lower than the 5 ks timescale of our observations. ...
... concentrate on a sample of quasars at 1.4 z 3.9, finding an average v 0 ≈ 0.3 c and N H ≈ 4 × 10 23 cm −2 (which, once relativistically corrected for 0.3c, corresponds to ).Nardini et al. (2015) andTombesi et al. (2015) both found similar v for the UFOs in PDS 456 (z = 0.184) and in IRAS F1119+3257 (z = 0.189), respectively. ...
We report on the 2019 XMM-Newton+NuSTAR monitoring campaign of the Seyfert galaxy NGC 2992, observed at one of its highest flux levels in the X-rays. The time-averaged spectra of the two XMM-Newton orbits show ultrafast outflows (UFOs) absorbing structures above 9 keV with >3 σ significance. A detailed investigation of the temporal evolution on a ∼5 ks timescale reveals UFO absorption lines at a confidence level >95% (2 σ ) in 8 out of 50 XMM-Newton segments, estimated via Monte Carlo simulations. We observe a wind variability corresponding to a length scale of 5 Schwarzschild radii r S . Adopting the novel Wind in the Ionized Nuclear Environment model, we estimate the outflowing gas velocity ( v = 0.21–0.45 c ), column density ( N H = 4–8 × 10 ²⁴ cm ⁻² ) and ionization state ( log ( ξ 0 / erg cm s − 1 ) = 3.7 – 4.7 ), taking into account geometrical and special relativity corrections. These parameters lead to instantaneous mass outflow rates of M ̇ out ≃ 0.3 – 0.8 M ⊙ yr ⁻¹ , with associated outflow momentum rates p ̇ out ≃ 20 – 90 L Bol / c and kinetic energy rates E ̇ K ≃ 2 – 25 L Bol . We estimate a wind duty cycle of ≈12% and a total mechanical power of ≈2 times the active galactic nuclei (AGN) bolometric luminosity, suggesting that the wind may drive significant feedback effects between the AGN and the host galaxy. Notably, we also provide an estimate for the wind launching radius and density of ≈5 r S , 10 ¹¹ cm ⁻³ , respectively.
... NGC 1365: Risaliti et al. 2005;Walton et al. 2014), some sources have been also observed to vary dramatically in the X-ray intrinsic flux. Recent long XMM-Newton and NuSTAR observations of highly variable sources have led to a number of results which shed light on the accretion/ejection mechanisms in their innermost regions, such as PDS 456 (Nardini et al. 2015;Reeves et al. 2018), IRAS 13349+2438 , IRAS 13224-3809 (Parker et al. 2017), MCG-03-58-007 (Braito et al. 2021) and NGC 3783 (Costanzo et al. 2021) among the others. ...
... Interestingly, UFOs detected in Quasars show higher v 0 , N H with respect to Seyfert galaxies; as an example, Chartas et al. (2021) concentrate on a sample of Quasars at 1.4 ≤ z ≤ 3.9, finding an average v 0 ≈ 0.3 c and N H ≈ 4 · 10 23 cm −2 (which, once relativistically corrected for 0.3 c, corresponds to N rel H ∼ 8 · 10 23 cm −2 ). Nardini et al. (2015) and Tombesi et al. (2015) both found similar v 0 ≈ 0.25c, N rel H ≈ 1.2 · 10 24 cm −2 for the UFOs in PDS 456 (z=0.184) and in IRASF1119+3257 (z=0.189), respectively. ...
... Equation 4 is calculated under the assumption of a spherical symmetric flow (Crenshaw et al. 2003;Crenshaw & Kraemer 2012), as commonly assumed for UFOs (see e.g. Tombesi et al. 2012;Nardini et al. 2015;Fiore et al. 2017;Chartas et al. 2021). However, the outflow in NGC 2992 shows a very low duty cycle and a short term variation of its spectral appearance, equal or lower than the 5 ks time scale of our observations. ...
We report on the 2019 XMM-Newton+NuSTAR monitoring campaign of the Seyfert galaxy NGC 2992, observed at one of its highest flux levels in the X-rays. The time-averaged spectra of the two XMM-Newton orbits show Ultra Fast Outflows (UFOs) absorbing structures above 9 keV with $> 3 \sigma$ significance. A detailed investigation of the temporal evolution on a $\sim$5 ks time scale reveals UFO absorption lines at a confidence level $>$95% (2$\sigma$) in 8 out of 50 XMM-Newton segments, estimated via Monte Carlo simulations. We observe a wind variability corresponding to a length scale of 5 Schwarzschild radii $r_S$. Adopting the novel Wind in the Ionised Nuclear Environment (WINE) model, we estimate the outflowing gas velocity ($v=0.21-0.45 c$), column density ($N_H=4-8\cdot 10^{24} cm^{-2}$) and ionisation state ($\log(\xi_0/erg\ cm\ s^{-1})=3.7-4.7$), taking into account geometrical and special relativity corrections. These parameters lead to instantaneous mass outflow rates $\dot{M}_{out}\simeq0.3-0.8 M_{\odot} yr^{-1}$, with associated outflow momentum rates $\dot{p}_{out}\simeq 20-90 L_{Bol}/c$ and kinetic energy rates $\dot{E}_K \simeq 2-25 L_{Bol}$. We estimate a wind duty cycle $\approx$ 12% and a total mechanical power $\approx$ 2 times the AGN bolometric luminosity, suggesting the wind may drive significant feedback effects between the AGN and the host galaxy. Notably, we also provide an estimate for the wind launching radius and density $\approx 5 r_S, 10^{11} {cm}^{-3}$, respectively.
... Outflows and winds from AGNs are thought to be the main drivers of feedback between AGN activity and star formation in their host galaxies (e.g., King & Pounds 2015;Fiore et al. 2017) in one of the three forms. (1) Highly ionized winds, with an ionization parameter of ξ ∼ 10 3 -10 6 erg cm −2 s −1 , are often detected through absorption lines of highly ionized gas, usually Fe XXV and Fe XXVI (e.g., Chartas et al. 2003;Tombesi et al. 2010;Nardini et al. 2015), with relativistic velocities in the range v ∼ 0.03c-0.3c (Chartas et al. 2003;Pounds et al. 2003;Reeves et al. 2003;Tombesi et al. 2010), the so-called ultrafast outflows (UFOs; e.g., Pounds et al. 2003;Tombesi et al. 2013). ...
... v ∼ 0.03c-0.3c, frequently associated with highly ionized Fe XXV or Fe XXVI species (e.g., Tombesi et al. 2010Tombesi et al. , 2014Gofford et al. 2013;Chartas et al. 2021; also the P Cygni-like profile in Nardini et al. 2015). ...
We present Chandra ACIS-S imaging spectroscopy results of the extended (1.″5–8″, 300–1600 pc) hard X-ray emission of NGC 5728, the host galaxy of a Compton-thick active galactic nucleus. We find spectrally and spatially resolved features in the Fe K α complex (5.0–7.5 keV) redward and blueward of the neutral Fe line at 6.4 keV in the extended narrow-line region bicone. A simple phenomenological fit of a power law plus Gaussians gives a significance of 5.4 σ and 3.7 σ for the red and blue wings, respectively. Fits to a suite of physically consistent models confirm a significance of ≥3 σ for the red wing. The significance of the blue wing may be diminished by the presence of rest-frame highly ionized Fe xxv and Fe xxvi lines (1.4 σ –3.7 σ range). A detailed investigation of the Chandra ACIS-S point-spread function and comparison with the observed morphology demonstrates that these red and blue wings are radially extended (∼5″, ∼1 kpc) along the optical bicone axis. If the wing emission is due solely to redshifted and blueshifted high-velocity neutral Fe K α , then the implied line-of-sight velocities are +/− ∼0.1 c , and their fluxes are consistent with being equal. A symmetric high-velocity outflow is then a viable explanation. This outflow has deprojected velocities ∼100 times larger than the outflows detected in optical spectroscopic studies, potentially dominating the kinetic feedback power.
... The equivalent width (EW) of the absorption profile is also high, with EW = −410 ± 80 eV (Laurenti et al. 2021), one of the highest found for UFOs to date (see Tombesi et al. 2010;Gofford et al. 2013) and implies that the column density may reach up to N H = 10 24 cm −2 . As shown by Laurenti et al. (2021), the iron line profile of the 2017 observation can be fitted with a disk-wind profile, via the WINE code of Luminari et al. (2018), which is reminiscent of the wind profile observed for the high-luminosity QSO PDS 456 (Nardini et al. 2015). ...
... Therefore, the combination of both the wind emission, in the form of the broad Fe Kα line, and the absorption along the line of sight, are important in determining the total mass outflow rate. Indeed, this allowed a realistic estimate of the mass outflow rate for the prototype disk-wind case of PDS 456, via both its wind emission and absorption (Nardini et al. 2015). ...
PG 1448+273 is a luminous, nearby ( z = 0.0645), narrow-line Seyfert 1 galaxy, which likely accretes close to the Eddington limit. XMM-Newton observations of PG 1448+273 in 2017 revealed the presence of an ultrafast outflow, as seen through its blueshifted iron K absorption profile, with an outflow velocity of about 0.1 c . Here, the first NuSTAR observation of PG 1448+273, performed in 2022 and coordinated with XMM-Newton, is presented, which shows remarkable variability of its ultrafast outflow. The average count rate is a factor of 2 lower during the last 60 ks of the NuSTAR observation, where a much faster component of the ultrafast outflow was detected with a terminal velocity of 0.26 ± 0.04 c . This is significantly faster than the outflow component that was initially detected in 2017, when overall PG 1448+273 was observed at a lower X-ray flux, and which implies an order of magnitude increase in the wind kinetic power between the 2017 and 2022 epochs. Furthermore, the rapid variability of the ultrafast outflow in 2022, on timescales down to 10 ks, suggests we are viewing through a highly inhomogeneous disk wind in PG 1448+273, where the passage of a denser wind clump could account for the increase in obscuration in the last 60 ks of the NuSTAR observation.
... 2020 ). Actively accreting BHs in active galactic nuclei (AGNs) can impact the host galaxy through a variety of feedback mechanisms, including fast accretion-driven winds (Faucher-Gigu ère & Quataert 2012 ; Zubovas & Nayakshin 2012 ;Tombesi et al. 2013 ;Nardini et al. 2015 ), galaxy-scale outflows (Feruglio et al. 2010 ;Sturm et al. 2011 ;Greene, Zakamska & Smith 2012 ;Cicone et al. 2014 ;Garc ía-Burillo et al. 2014 ;Zakamska & Greene 2014 ;Circosta et al. 2018 ;Wylezalek et al. 2020 ;Ramos Almeida et al. 2022 ), and largescale jets (Fabian 2012 ). Observational constraints on the efficiency of AGN feedback suggest that massive BHs may play a key role in galaxy evolution by injecting energy and momentum into the interstellar medium (ISM) and circumgalactic medium (CGM) of galaxies (Hopkins & Elvis 2010 ;Alexander & Hickox 2012 ;Fabian 2012 ;Alatalo et al. 2015 ;Wylezalek & Zakamska 2016 ;Fiore et al. 2017 ;Harrison 2017 ;Harrison et al. 2018 ). ...
... Our AGN wind model is specified by the following main properties: the mass outflow rate Ṁ w , the initial wind velocity v w , and the geometry of the wind. We consider that a fraction k of the AGN bolometric luminosity ( L bol ≡ 0 . 1 Ṁ BH c 2 ) emerges as a fast, nuclear isotropic wind radially outwards from the BH, with initial velocity v w = 30 000 km s −1 and temperature T w ∼ 10 4 K, typical of broad absorption-line winds and ultrafast outflows (Weymann, Carswell & Smith 1981 ;Gibson et al. 2009 ;Feruglio et al. 2015 ;Nardini et al. 2015 ;Tombesi et al. 2015 ). We assume that the wind immediately interacts with the ambient medium, with postshock velocity and temperature given by v sh = v w / 4 = 7 , 500 km s −1 and T sh ≈ 1.2 × 10 10 K (Faucher-Gigu ère & Quataert 2012 ). ...
Negative feedback from accreting supermassive black holes is considered crucial in suppressing star formation and quenching massive galaxies. However, several models and observations suggest that black hole feedback may have a positive effect, triggering star formation by compressing interstellar medium gas to higher densities. We investigate the dual role of black hole feedback using cosmological hydrodynamic simulations from the Feedback In Realistic Environments (FIRE) project, incorporating a novel implementation of hyper-refined accretion-disc winds. Focusing on a massive, star-forming galaxy at z ∼ 2 (Mhalo ∼ 1012.5 M⊙), we demonstrate that strong quasar winds with a kinetic power of ∼1046 erg/s, persisting for over 20 Myr, drive the formation of a central gas cavity and significantly reduce the surface density of star formation across the galaxy’s disc. The suppression of star formation primarily occurs by limiting the availability of gas for star formation rather than by evacuating the pre-existing star-forming gas reservoir (preventive feedback dominates over ejective feedback). Despite the overall negative impact of quasar winds, we identify several potential indicators of local positive feedback, including: (1) the spatial anti-correlation between wind-dominated regions and star-forming clumps, (2) higher local star formation efficiency in compressed gas at the edge of the cavity, and (3) increased contribution of outflowing material to local star formation. Moreover, stars formed under the influence of quasar winds tend to be located at larger radial distances. Our findings suggest that both positive and negative AGN feedback can coexist within galaxies, although the local positive triggering of star formation has a minor influence on global galaxy growth.
... Conversely, outflows inferred from blueshifted Fe XXV/ XXVI absorption lines in the X-ray band at rest-frame energies E > 7 keV are observed in AGNs at subparsec scales consistent with an accretion disk interpretation. These ultrafast outflows (UFOs; Tombesi et al. 2010Tombesi et al. , 2011Tombesi et al. , 2015Gofford et al. 2013;Tombesi & Cappi 2014;Longinotti et al. 2015;Nardini et al. 2015;Parker et al. 2017) have outflow velocities that are mildly relativistic (v out ∼0.1c). Confirming both a large-scale galactic outflow and sub-parsec scale accretion disk wind in the same object presents observational challenges requiring simultaneous detection of the outflow in the X-rays and at lower energies (mm-optical-IR). ...
... The solid and dashed horizontal lines indicate the 1σ, 90%, and 3σ confidence ranges for the value of the redshift of the absorber, which is well constrained at z=−0.07 in the observed frame corresponding to an outflowing velocity of 0.11c. luminous quasars (e.g.,Tombesi et al. 2012Tombesi et al. , 2015Gofford et al. 2015;Nardini et al. 2015;Fiore et al. 2017). The accretion disk wind is consistent with having a momentum rate comparable to the AGN radiation pressure, and the energetics are high enough to influence AGN feedback (e.g.,Di Matteo et al. 2005;Hopkins & Elvis 2010;Gaspari et al. 2011). ...
We present new XMM-Newton and NuSTAR observations of the galaxy merger IRAS F05189-2524, which is classified as an ultraluminous infrared galaxy and optical Seyfert 2 at z = 0.0426. We test a variety of spectral models that yield a best fit consisting of an absorbed power law with emission and absorption features in the Fe K band. Remarkably, we find evidence for a blueshifted Fe K absorption feature at E = 7.8 keV (rest frame) which implies an ultrafast outflow (UFO) with v out = 0.11 ± 0.01 c . We calculate that the UFO in IRAS F05189-2524 has a mass outflow rate of yr ⁻¹ , a kinetic power of 8% L AGN , and a momentum rate (or force) of . Comparing the energetics of the UFO to the observed multi-phase outflows at kiloparsec scales yields an efficiency factor of f ∼ 0.05 for an energy-driven outflow. Given the uncertainties, however, we cannot exclude the possibility of a momentum-driven outflow. Comparing IRAS F05189-2524 with nine other objects with observed UFOs and large-scale galactic outflows suggests that there is a range of efficiency factors for the coupling of the energetics of the nuclear and galaxy-scale outflows that likely depend on specific physical conditions in each object.
... Actively accreting BHs in active galactic nuclei (AGN) can impact the host galaxy through a variety of feedback mechanisms, includ-E-mail: jonathan.mercedes_feliz@uconn.edu ing fast accretion-driven winds (Faucher-Giguère & Quataert 2012;Zubovas & Nayakshin 2012;Tombesi et al. 2013;Nardini et al. 2015), galaxy-scale outflows (Feruglio et al. 2010;Sturm et al. 2011;Greene et al. 2012;Cicone et al. 2014;Zakamska & Greene 2014;Wylezalek et al. 2020;Ramos Almeida et al. 2022), and large scale jets (Fabian 2012). Observational constraints on the efficiency of AGN feedback suggest that massive BHs may play a key role in galaxy evolution by injecting energy and momentum into the interstellar medium (ISM) and circumgalactic medium (CGM) of galaxies (Hopkins & Elvis 2010;Alexander & Hickox 2012;Fabian 2012;Alatalo et al. 2015;Wylezalek & Zakamska 2016;Fiore et al. 2017;Harrison 2017;Harrison et al. 2018). ...
... Our AGN wind model is specified by the following main properties: the mass outflow rateṀ w , the initial wind velocity v w , and the geometry of the wind. We consider that a fraction k of the AGN bolometric luminosity (L bol ≡ 0.1Ṁ BH c 2 ) emerges as a fast, nuclear isotropic wind radially outward from the BH, with initial velocity v w = 30, 000 km s −1 and temperature T w ∼ 10 4 K, typical of broad absorption line winds and ultrafast outflows (Weymann et al. 1981;Gibson et al. 2009;Feruglio et al. 2015;Nardini et al. 2015;Tombesi et al. 2015). We assume that the wind immediately interacts with the ambient medium, with post-shock velocity and temperature given by v sh = v w /4 = 7, 500 km s −1 and T sh ≈ 1.2 × 10 10 K (Faucher-Giguère & Quataert 2012). ...
Negative feedback from accreting supermassive black holes is regarded as a key ingredient in suppressing star formation and quenching massive galaxies. However, several models and observations suggest that black hole feedback may have a positive effect, triggering star formation by compressing interstellar medium gas to higher densities. We investigate the dual role of black hole feedback using cosmological hydrodynamic simulations from the Feedback In Realistic Environments (FIRE) project, including a novel implementation of hyper-refined accretion-disc winds. Focusing on a massive, star-forming galaxy at $z \sim 2$ ($M_{\rm halo} \sim 10^{12.5} \, {\rm M}_{\odot}$), we show that strong quasar winds with kinetic power $\sim$10$^{46}$ erg/s acting for $>$20$\,$Myr drive the formation of a central gas cavity and can dramatically reduce the star formation rate surface density across the galaxy disc. The suppression of star formation is primarily driven by reducing the amount of gas that can become star-forming, compared to directly evacuating the pre-existing star-forming gas reservoir (preventive feedback dominates over ejective feedback). Despite the global negative impact of quasar winds, we identify several plausible signatures of local positive feedback, including: (1) spatial anti-correlation of wind-dominated regions and star-forming clumps, (2) higher local star formation efficiency in compressed gas near the edge of the cavity, and (3) increased local contribution of outflowing material to star formation. Stars forming under the presence of quasar winds tend to do so at larger radial distances. Our results suggest that positive and negative AGN feedback can coexist in galaxies, but local positive triggering of star formation plays a minor role in global galaxy growth.
... In parallel to grating observations with Chandra and XMM-Newton, intensive observations primarily carried out at CCD resolution of Seyfert AGNs (including radio-quiet, radio-loud, and nearby/lensed quasars, for example) have revealed ultrafast outflows (UFOs) exhibiting a distinct property, i.e., a massive column (N H 10 24 cm −2 ) with higher ionization parameter ( xlog 4 6 -) outflowing at a near-relativistic velocity (v out /c 0.1-0.7) in large contrast with the properties of conventional warm absorbers, as described earlier. The most prominent UFO features detected in the X-ray spectrum are usually Fe K absorption lines attributed to Fe XXV/Fe XXVI ions (e.g., Pounds et al. 2003;Reeves et al. 2003Reeves et al. , 2009Reeves et al. , 2018aChartas et al. 2009;Tombesi et al. 2010aTombesi et al. , 2010bTombesi et al. , 2011Tombesi et al. , 2012Tombesi et al. , 2013Tombesi et al. , 2015Nardini et al. 2015;Parker et al. 2017). With an increasing number of multiepoch observations in search of Fe K UFOs across diverse AGN populations, it is shown that UFOs can be highly variable on a timescale of at least days (e.g., Reeves et al. 2018b), and there appear to be likely correlations among the observed quantities (e.g., N H , v out , equivalent width, EW, and spectral hardness Γ; e.g., see, Chartas et al. 2009;Matzeu et al. 2017;Parker et al. 2018;Pinto et al. 2018, but also see, e.g., Chartas & Canas 2018;Boissay-Malaquin et al. 2019). ...
... Such emission processes might be important to accurately assess the physical properties of ionized absorbers because they can "fill in" the intrinsic absorption features. For example, some very luminous quasars accreting at near-Eddington rates, such as PDS 456, are found to show a broad P-Cygni profile in the Fe K band associated with their prototype UFOs, where the wind may well be Compton-thick (Nardini et al. 2015). On the other hand, one of the well-studied Seyfert 1 AGNs showing canonical X-ray warm absorbers, NGC 3783, is also known to exhibit a handful emission lines in the UV/soft X-ray bands mostly from the He-like triplets (resonance, intercombination, and forbidden lines) of O VII, Ne IX, and Mg XI as well as Lyα lines from the H-like species of these elements with a very small systematic velocity shift (130 ± 290 km s −1 ; e.g., Kaspi et al. 2000;Gabel et al. 2005;Kallman et al. 2009). ...
We aim to explore spectral signatures of the predicted multi-ion ultrafast outflows (UFOs) in the broadband X-ray spectra of active galactic nuclei by exploiting an accretion disk-wind model in the context of a simple magnetohydrodynamic (MHD) framework. We are focused primarily on examining the spectral dependences on a number of key properties: (1) ionizing luminosity ratio λ ion , (2) line-of-sight wind density slope p , (3) optical/UV-to-X-ray strength α OX , (4) inclination θ , (5) X-ray photon index Γ, and (6) wind density factor f D . With an emphasis on radio-quiet Seyferts in the sub-Eddington regime, multi-ion UFO spectra are systematically calculated as a function of these parameters to show that MHD-driven UFOs imprint a unique asymmetric absorption line profile with a pronounced blue tail structure on average. Such a characteristic line signature is generic to the simplified MHD disk-wind models presented in this work due to their specific kinematics and density structure. The properties of these absorption line profiles could be utilized as a diagnostics to distinguish between different wind-driving mechanisms or even the specific values of given MHD wind parameters. We also present high-fidelity microcalorimeter simulations in anticipation of the upcoming XRISM/Resolve and Athena/X-IFU instruments to demonstrate that such a “tell-tale” sign may be immune to a spectral contamination by the presence of additional warm absorbers and partially covering gas.
... UFOs are the most extreme subset of AGN winds, with velocities greater than 10,000 km s −1 . They are believed to originate from the inner accretion disk within a few hundred gravitational radii from the black hole (Tombesi et al. 2010;Nardini et al. 2015). The existence of a UFO has been confirmed in 1H 0707−495 (Dauser et al. 2012;Hagino et al. 2016;Kosec et al. 2018) at a velocity of ∼0.13c with an ionization parameter log(ξ/erg cm s −1 ) ∼ 4.3. ...
We use near-infrared spectroscopy covering simultaneously the zJHK bands to look for outflowing gas from the nuclear environment of 1H 0707−495 taking advantage that this region is dominated by low-ionization broad-line region lines, most of them isolated. We detect broad components in H i , Fe ii , and O i , at rest to the systemic velocity, displaying FWHM values of ∼500 km s ⁻¹ , consistent with its classification as a narrow-line Seyfert 1 active galactic nucleus. Moreover, most lines display a conspicuous blue-asymmetric profile, modeled using a blueshifted component, whose velocity shift reaches up to ∼826 km s ⁻¹ . This last feature can be interpreted in terms of outflowing gas already observed in X-ray and UV lines in 1H 0707−495 but not detected before in the low-ionization lines. We discuss the relevance of our findings within the framework of the wind scenario already proposed for this source and suggest that the wind extends well into the narrow-line region owing to the observation of a blueshifted component in the forbidden line of [S iii ] λ 9531.
... is the gravitational radius of the black hole. Instantaneous quantities such as the mass outflow rate can then be estimated as (Nardini et al. 2015 ...
Supermassive black holes can experience super-Eddington peak mass fallback rates following the tidal disruption of a star. The theoretical expectation is that part of the infalling material is expelled by means of an accretion disk wind, whose observational signature includes blueshifted absorption lines of highly ionized species in X-ray spectra. To date, however, only one such ultrafast outflow (UFO) has been reported in the tidal disruption event (TDE) ASASSN–14li. Here we report on the discovery of a transient absorption-like signature in X-ray spectra of the TDE AT2020ksf/Gaia20cjk (at a redshift of z = 0.092), following an X-ray brightening ∼230 days after UV/optical peak. We find that while no statistically significant absorption features are present initially, they appear on a timescale of several days and remain detected up to 770 days after peak. Simple thermal continuum models, combined with a power-law or neutral absorber, do not describe these features well. Adding a partial-covering, low-velocity ionized absorber improves the fit at early times but fails at late times. A high-velocity ( v w ∼ 42,000 km s ⁻¹ ), ionized absorber (UFO) provides a good fit to all data. The few-day timescale of variability is consistent with expectations for a clumpy wind. We discuss several scenarios that could explain the X-ray delay, as well as the potential for larger-scale wind feedback. The serendipitous nature of the discovery could suggest a high incidence of UFOs in TDEs, alleviating some of the tension with theoretical expectations.
... If UFOs can be driven at substantially sub-Eddington luminosities, the time over which this feedback mode can operate may be longer by roughly an order of magnitude. Many other well-known UFOs found in AGN, such as the strong X-ray outflow in PDS 456 (Nardini et al. 2015) and the X-ray and UV outflow in PG 1211+143 (e.g., Reeves et al. 2018;Kriss et al. 2018), are plausibly the result of quasi-or super-Eddington accretion within those systems. The finding that UFOs and strong feedback can be driven in Mrk 817 at λ ∼ 0.008-0.016 ...
Mrk 817 is a bright and variable Seyfert 1.2 active galactic nucleus (AGN). X-ray monitoring of Mrk 817 with the Neil Gehrels Swift Observatory in 2022 revealed that the source flux had declined to a lower level than recorded at any prior point in the then 19 yr mission. We present an analysis of deep XMM-Newton and NuSTAR observations obtained in this low flux state. The spectra reveal a complex X-ray wind consisting of neutral and ionized absorption zones. Three separate velocity components are detected as part of a structured ultrafast outflow (UFO), with v / c = 0.043 − 0.003 + 0.007 , v / c = 0.079 − 0.0008 + 0.003 , and v / c = 0.074 − 0.005 + 0.004 . These projected velocities suggest that the wind likely arises at radii that are much smaller than the optical broad-line region. In order for each component of the outflow to contribute significant feedback, the volume filling factors must be greater than f ≃ 0.009, f ≃ 0.003, and f ≃ 0.3, respectively. For plausible, data-driven volume filling factors, these limits are passed, and the total outflow likely delivers the fierce feedback required to reshape its host environment, despite a modest radiative Eddington fraction of λ ≃ 0.008–0.016 (this range reflects plausible masses). UFOs are often detected at or above the Eddington limit; this result signals that black hole accretion has the potential to shape host galaxies even at modest Eddington fractions and over a larger fraction of a typical AGN lifetime. We discuss our findings in terms of models for disk winds and black hole feedback in this and other AGN.
... c, where c is the speed of light. Since UFOs are likely to have larger solid angles than the relativistic jets (e.g., Nardini et al. 2015, Hagino et al. 2015, UFO contribution to the co-evolution of the SMBHs and the host galaxies may be comparable to or even exceed that of the jets (e.g., King 2010, King & Pounds 2015. ...
Recent radiation-magnetohydrodynamic simulations of active galactic nuclei predict the presence of the disk winds, which may get unstable and turn into fragmented clumps far from the central black hole. These inner winds and the outer clumps may be observed as the ultrafast outflows (UFOs) and the partial absorbers, respectively. However, it is challenging to observationally constrain their origins because of the complicated spectral features and variations. To resolve such degeneracies of the clumpy absorbers and other components, we developed a novel ``spectral-ratio model fitting'' technique that estimates the variable absorbing parameters from the ratios of the partially absorbed spectra to the non-absorbed one, canceling the complex non-variable spectral features. We applied this method to the narrow-line Seyfert 1 galaxy \iras observed by \xmm in 2016 for $\sim$1.5 Ms. As a result, we found that the soft spectral variation is mostly caused by changes in the partial covering fraction of the mildly-ionized clumpy absorbers, whose outflow velocities are similar to those of the UFO ($\sim$0.2--0.3 $c$). Furthermore, the velocities of the clumpy absorbers and UFOs increase similarly with the X-ray fluxes, consistent with the change in the UV-dominant continuum flux. We also discovered a striking correlation between the clump covering fraction and the equivalent width of the UFO absorption lines, which indicates that increasing the outflow in the line-of-sight lead to more prominent UFOs and more partial absorption. These findings strongly suggest that the clumpy absorbers and the UFO share the same origin, driven by the same UV-dominant continuum radiation.
... The classical warm absorbers are identified with multiple narrow absorption lines with a typical outflow velocity of ≲ 10 3 km s −1 [15][16][17][18][19][20][21]. Ultrafast outflows are mainly inferred from the absorption features of highly ionized Fe xxvi and/or Fe xxv in the hard X-ray band [22][23][24][25][26]. The outflow velocity of ultrafast outflows can reach up to about a third of the speed of light (∼ 10 4−5 km s −1 ). ...
The Hot Universe Baryon Surveyor (HUBS) is a proposed space-based X-ray telescope for detecting X-ray emissions from the hot gas content in our universe. With its unprecedented spatially-resolved high-resolution spectroscopy and large field of view, the HUBS mission will be uniquely qualified to measure the physical and chemical properties of the hot gas in the interstellar medium, the circumgalactic medium, the intergalactic medium, and the intracluster medium. These measurements will be valuable for two key scientific goals of HUBS, namely to unravel the AGN and stellar feedback physics that governs the formation and evolution of galaxies, and to probe the baryon budget and multi-phase states from galactic to cosmological scales. In addition to these two goals, the HUBS mission will also help us solve some problems in the fields of galaxy clusters, AGNs, diffuse X-ray backgrounds, supernova remnants, and compact objects. This paper discusses the perspective of advancing these fields using the HUBS telescope.
... The extent and importance of various mechanisms via which the galaxy and black hole regulate each other's growth are still debated (e.g., Harrison 2017), as are the dominant triggers of accretion onto galactic SMBHs, hence, the onset of active galactic nucleus (AGN) activity, even for the most luminous AGN found in quasi-stellar objects (QSOs; e.g., Sharma et al. 2021). Outflows at different spatial scales have been discovered in quasars 8 in molecular (e.g., Spoon et al. 2013;Alatalo 2015;Feruglio et al. 2015;Vayner et al. 2021), atomic (e.g., Morganti & Oosterloo 2018), and ionized gas (e.g., Rupke & Veilleux 2013;Veilleux et al. 2021), with evidence that some are powerful enough to be the main AGN feedback agent (e.g., Harrison et al. 2014;Nardini et al. 2015;Miller et al. 2020). Yet, strong observational evidence is missing of the role mergers play in contributing to the emergence of such outflows in quasars, and the extent to which they affect the environment on galactic scales. ...
Low-ionization broad absorption line QSOs (LoBALs) are suspected to be merging systems in which extreme, active galactic nucleus-driven outflows have been triggered. Whether or not LoBALs are uniquely associated with mergers, however, has yet to be established. To characterize the morphologies of LoBALs, we present the first high-resolution morphological analysis of a volume-limited sample of 22 Sloan Digital Sky Survey (SDSS)-selected LoBALs at 0.5 < z < 0.6 from Hubble Space Telescope Wide Field Camera 3 observations. Host galaxies are resolved in 86% of the systems in F125W, which is sensitive to old stellar populations, while only 18% are detected in F475W, which traces young, unobscured stellar populations. Signs of recent or ongoing tidal interaction are present in 45%–64% of the hosts, including double nuclei, tidal tails, bridges, plumes, shells, and extended debris. Ongoing interaction with a companion is apparent in 27%−41% of the LoBALs, with as much as 1/3 of the sample representing late-stage mergers at projected nuclear separations <10 kpc. Detailed surface brightness modeling indicates that 41% of the hosts are bulge dominated while only 18% are disks. We discuss trends in various properties as a function of merger stage and parametric morphology. Notably, mergers are associated with slower, dustier winds than those seen in undisturbed/unresolved hosts. Our results favor an evolutionary scenario in which quasar-level accretion during various merger stages is associated with the observed outflows in low- z LoBALs. We discuss differences between LoBALs and FeLoBALs and show that selection via the traditional balnicity index would have excluded all but one of the mergers.
... , e.g. Nardini et al. 2015;Kosec et al. 2020;Parker et al. 2021;Xu et al. 2021a;Matzeu et al. 2022a). The column density ( H ∼ 2.3 × 10 21 cm −2 ) is not as thick as typical UFOs discovered from Fe K absorption feature (log( H /cm −2 ) ∼ 22-24). ...
Ultra-fast outflows (UFOs) have been revealed in a large number of active galactic nuclei (AGN) and are regarded as promising candidates for AGN feedback on the host galaxy. The nature and launching mechanism of UFOs are not yet fully understood. Here we perform a time- and flux-resolved X-ray spectroscopy on four XMM-Newton observations of a highly accreting narrow-line Seyfert 1 (NLS1) galaxy, Mrk 1044, to study the dependence of the outflow properties on the source luminosity. We find that the UFO in Mrk 1044 responds to the source variability quickly and its velocity increases with the X-ray flux, suggesting a high-density ($10^{9}-4.5\times10^{12}\,\mathrm{cm}^{-3}$) and radiatively driven outflow, launched from the region within a distance of $98-6600\, R_\mathrm{g}$ from the black hole. The kinetic energy of the UFO is conservatively estimated ($L_\mathrm{UFO}\sim4.4\%L_\mathrm{Edd}$), reaching the theoretical criterion to affect the evolution of the host galaxy. We also find emission lines, from a large-scale region, have a blueshift of $2700-4500$ km/s in the spectra of Mrk 1044, which is rarely observed in AGN. By comparing with other sources, we propose a correlation between the blueshift of emission lines and the source accretion rate, which can be verified by a future sample study.
... It has been proposed that one of the channels of forming such massive black holes would be via gas accretion at rates comparable/higher than the Eddington limit (Johnson & Haardt 2016 ). In addition, these sources are thought to launch powerful nuclear outflows (Nardini et al. 2015 ;Matzeu et al. 2017 ), imprinting absorption lines in the X-ray spectra (especially in the 6-8 keV range), that are capable of regulating the growth and the evolution of their host galaxies (e.g. King & Pounds 2015 ;Giustini & Proga 2019 ). ...
SMSS J114447.77-430859.3 (z = 0.83) has been identified in the SkyMapper Southern Survey as the most luminous quasar in the last $\sim 9\, \rm Gyr$ . In this paper, we report on the eROSITA/Spectrum–Roentgen–Gamma (SRG) observations of the source from the eROSITA All Sky Survey, along with presenting results from recent monitoring performed using Swift, XMM-Newton, and NuSTAR. The source shows a clear variability by factors of ∼10 and ∼2.7 over time-scales of a year and of a few days, respectively. When fit with an absorbed power law plus high-energy cutoff, the X-ray spectra reveal a Γ = 2.2 ± 0.2 and $E_{\rm cut}=23^{+26}_{-5}\, \rm keV$ . Assuming Comptonization, we estimate a coronal optical depth and electron temperature of $\tau =2.5-5.3\, (5.2-8)$ and $kT=8-18\, (7.5-14)\, \rm keV$ , respectively, for a slab (spherical) geometry. The broadband SED is successfully modelled by assuming either a standard accretion disc illuminated by a central X-ray source, or a thin disc with a slim disc emissivity profile. The former model results in a black hole mass estimate of the order of $10^{10}\, \mathrm{ M}_\odot$ , slightly higher than prior optical estimates; meanwhile, the latter model suggests a lower mass. Both models suggest sub-Eddington accretion when assuming a spinning black hole, and a compact ($\sim 10\, r_{\rm g}$ ) X-ray corona. The measured intrinsic column density and the Eddington ratio strongly suggest the presence of an outflow driven by radiation pressure. This is also supported by variation of absorption by an order of magnitude over the period of $\sim 900 \ \rm d$ .
... The appropriate mass loading and wind velocity depend on the resolution of the simulation, which sets the physical scale at injection and therefore the type of winds that are represented. High resolution simulations (usually idealized) can attempt to model nuclear winds similar to those observed in broad absorption line QSOs 176 and in absorption against X-ray emission from AGN, 155,156,177 with mildly relativistic velocity (v out ∼ 30, 000kms −1 ) and mass outflow rate comparable to the black hole accretion rate (η m ∼ 1). 138,[172][173][174]178 These winds appear to generate on accretion-disk scales (<100R s ) and are broadly consistent with predictions from accretion disk simulations, corresponding to a kinetic energy efficiency k ∼ 0.05 similar to the feedback coupling efficiency used in simulations implementing thermal feedback. ...
Massive black holes are fundamental constituents of our cosmos, from the Big Bang to today. Understanding their formation from cosmic dawn, their growth, and the emergence of the first, rare quasars in the early Universe remains one of our greatest theoretical and observational challenges. Hydrodynamic cosmological simulations self-consistently combine the processes of structure formation at cosmological scales with the physics of smaller, galaxy scales. They capture our most realistic understanding of massive black holes and their connection to galaxy formation and have become the primary avenue for theoretical research in this field. The space-based gravitational wave interferometer, LISA, will open up new investigations into the dynamical processes involving massive black holes. Multi-messenger astrophysics brings new exciting prospects for tracing the origin, growth and merger history of massive black holes across cosmic ages.
... The extent and importance of various mechanisms via which the galaxy and black hole regulate each other's growth are still debated (e.g., Harrison 2017), as are the dominant triggers of accretion onto galactic SMBHs, hence, the onset of active galactic nucleus (AGN) activity, even for the most luminous AGN found in quasi-stellar objects (QSOs) (e.g., Sharma et al. 2021). Outflows at different spatial scales have been discovered in quasars 1 in molecular (e.g., Vayner et al. 2021;Alatalo 2015;Feruglio et al. 2015;Spoon et al. 2013), atomic (e.g., Morganti & Oosterloo 2018), and ionized gas (e.g., Veilleux et al. 2021;Rupke & Veilleux 2013), with evidence that some are powerful enough to be the main AGN feedback agent (e.g., Miller et al. 2020;Nardini et al. 2015;Harrison et al. 2014). Yet, strong observational evidence is missing of the role mergers play in contributing to the emergence of such outflows in quasars, and the extent to which they affect the environment on galactic scale. ...
Low-ionization Broad Absorption Line QSOs (LoBALs) are suspected to be merging systems in which extreme, AGN-driven outflows have been triggered. Whether or not LoBALs are uniquely associated with mergers, however, has yet to be established. To characterize the morphologies of LoBALs, we present the first high-resolution morphological analysis of a volume-limited sample of 22 SDSS-selected LoBALs at 0.5 < z < 0.6 from Hubble Space Telescope Wide Field Camera 3 observations. Host galaxies are resolved in 86% of the systems in F125W, which is sensitive to old stellar populations, while only 18% are detected in F475W, which traces young, unobscured stellar populations. Signs of recent or ongoing tidal interaction are present in 45-64% of the hosts, including double nuclei, tidal tails, bridges, plumes, shells, and extended debris. Ongoing interaction with a companion is apparent in 27-41% of the LoBALs, with as much as 1/3 of the sample representing late-stage mergers at projected nuclear separations <10 kpc. Detailed surface brightness modeling indicates that 41% of the hosts are bulge-dominated while only 18% are disks. We discuss trends in various properties as a function of merger stage and parametric morphology. Notably, mergers are associated with slower, dustier winds than those seen in undisturbed/unresolved hosts. Our results favor an evolutionary scenario in which quasar-level accretion during various merger stages is associated with the observed outflows in low-z LoBALs. We discuss differences between LoBALs and FeLoBALs and show that selection via the traditional Balnicity index would have excluded all but one of the mergers.
... UFOs could originate from accretion disc winds launched close to the central SMBH in AGNi (Tombesi et al. 2010;Tombesi et al. 2013;Tombesi et al. 2015;Gofford et al. 2013;Laurenti et al. 2021). They are indeed mildly relativistic flows characterized by a wide opening angle (Nardini et al. 2015), typically observed in the nearest parsecs from the SMBH (see also Laha et al. 2021, for a recent reviw). Similar to other astrophysical diverging flows, UFOs can feature a bubble structure (Faucher-Giguère & Quataert 2012) characterized by an inner wind termination shock and an outer forward shock (Zubovas & King 2012;Costa et al. 2014). ...
The enhanced activity typical of the core of Seyfert galaxies can drive powerful winds where high-energy phenomena can occur. In spite of their high power content, the number of such non-jetted active galactic nuclei detected in gamma-ray is very limited. In this Letter, we report the detection of a gamma-ray flux from NGC 4151, a Seyfert galaxy located at about 15.8 Mpc. The source is known for hosting ultra-fast outflows (UFOs) in its innermost core through X-ray spectroscopic observations, thereby becoming the first UFO host ever detected in gamma rays. UFOs are mildly relativistic, wide opening angle winds detected in the innermost parsecs of active galaxies where strong shocks can develop. We interpret the gamma-ray flux as a result of diffusive shock acceleration at the wind termination shock of the UFO and inelastic hadronic collisions in its environment. Interestingly, NGC 4151 is also spatially coincident with a weak excess of neutrino events identified by the IceCube neutrino observatory. We discuss the contribution of the UFO to such a neutrino excess.
... Galactic outflows manifest in a variety of different phases and with observational evidence spanning a wide range of frequencies. The sub-parsec, highly ionized outflows are primarily measured by X-ray absorption lines (Reeves et al. 2009;Tombesi et al. 2012Tombesi et al. , 2013Gofford et al. 2013;Nardini et al. 2015), whereas the neutral atomic phase is primarily measured by observations of the sodium doublet (Heckman et al. 2000;Rupke et al. 2005;Cazzoli et al. 2016;Roberts-Borsani & Saintonge 2019), and the molecular phase is measured through various radio, infrared (IR), and optical observations (Feruglio et al. 2010;Fischer et al. 2010;Sturm et al. 2011;Combes et al. 2013;Spoon et al. 2013;Veilleux et al. 2013;Cicone et al. 2014;García-Burillo et al. 2015;Stone et al. 2016;González-Alfonso et al. 2017;Bolatto et al. 2021;Stuber et al. 2021). Together, understanding the details of the various phases of galactic outflows helps to shed light on galactic structure and feedback in galaxies. ...
Many star-forming galaxies and those hosting active galactic nuclei show evidence of massive outflows of material in a variety of phases including ionized, neutral atomic, and molecular. Molecular outflows in particular have been the focus of recent interest as they may be responsible for removing gas from the galaxy, thereby suppressing star formation. As material is ejected from the cores of galaxies, interactions of the outflowing material with the interstellar medium can accelerate cosmic rays and produce high-energy gamma rays. In this work, we search for gamma-ray emission from a sample of local galaxies known to host molecular outflows using data collected by the Fermi Large Area Telescope. We employ a stacking technique in order to search for and characterize the average gamma-ray emission properties of the sample. Gamma-ray emission is detected from the galaxies in our sample at the 4.4 σ level with a power-law photon index of Γ ≈ 2 in the 1–800 GeV energy range. The emission is found to correlate with tracers of star formation activity, namely the 8–1000 μ m infrared luminosity. We also find that the observed signal can be predominantly attributed to H ii galaxies hosting energy-driven outflows. While we do not find evidence suggesting that the outflows are accelerating charged particles directly, galaxies with molecular outflows may produce more gamma rays than galaxies without outflows. In particular, the set consisting of gamma-ray-detected galaxies with molecular outflows are nearly perfect calorimeters and may be future targets for searches of high-energy neutrinos.
... The possible connection among the various types of ionized outflows was investigated in detail in Tombesi et al. (2013), where the comparison between the UFOs and the WAs suggests both types of ionized outflows belong to a single stratified outflow. Recent studies using high-resolution grating have detected UFOs in the soft X-rays (e.g., Ark 564, PDS 456, PG 1211+143, IRAS 17020+4544, Mrk 1044; Gupta et al. 2013;Longinotti et al. 2015;Nardini et al. 2015;Pounds et al. 2016b;Reeves et al. 2020;Krongold et al. 2021), typically with lower column densities and ionization parameters compared to those of the UFOs identified in the 6-9 keV range. Interestingly, the high-velocity UV counterparts to some of these UFOs have also been reported (Kraemer et al. 2012;Hamann et al. 2018;Kriss et al. 2018;Mehdipour et al. 2022) showing narrow and blueshifted absorption lines (e.g., HI Lyα, N V, C IV, etc.). ...
Narrow-line Seyfert 1 (NLS1) galaxies are an important type of active galactic nucleus (AGN), generally expected to be accreting at a high Eddington rate. The properties of their outflows and importance of AGN feedback remain intriguing. We report on the discovery of fast outflowing warm absorbers (WAs) in the NLS1 PG 1001+054 with velocities in the range of ∼7000–9000 km s ⁻¹ . They are identified with blueshifted Ly α , N v, and Si iv lines in the high-resolution ultraviolet (UV) spectra taken with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. We perform photoionization modeling using XSTAR with three WAs. The derived physical properties are typical of WAs in terms of ionization and column density, whereas the outflow velocities are significantly higher. The estimated location of these WAs ranges from 1 to 73 parsecs away from the AGN. Together with previous detection of high ionization absorbers in the X-ray for PG 1001+054, we suggest that fast outflowing UV absorbers are probably part of a multiphase outflow. Such a structure is likely produced by the outflow launched from the AGN at an accretion disk scale, which shocks the ambient interstellar medium (ISM), producing stratified absorbers. Assuming contribution from the three WAs at tens of parsecs, the estimated ratio between the kinetic power of the outflow and AGN Eddington luminosity could reach 1.7%, raising the possibility of sufficient influence on the host galaxy when compared to some theoretical models for efficient AGN feedback.
... Galactic outflows manifest in a variety of different phases and with observational evidence spanning a wide range of frequencies. The sub-pc highly-ionized outflows are primarily measured by X-ray absorption lines (Reeves et al. 2009;Tombesi et al. 2012Tombesi et al. , 2013Gofford et al. 2013;Nardini et al. 2015), whereas the neutral atomic phase is primarily measured by observations of the sodium doublet (Heckman et al. 2000;Rupke et al. 2005;Cazzoli et al. 2016;Roberts-Borsani & Saintonge 2019), and the molecular phase is measured through various radio, infrared, and optical observations (Fischer et al. 2010;Feruglio et al. 2010;Sturm et al. 2011;Combes et al. 2013;Spoon et al. 2013;Veilleux et al. 2013;Cicone et al. 2014;García-Burillo et al. 2015;Stone et al. 2016;González-Alfonso et al. 2017;Bolatto et al. 2021;Stuber et al. 2021). Together, understanding the details of the various phases of galactic outflows helps to shed light on galactic structure and feedback in galaxies. ...
Many star-forming galaxies and those hosting active galactic nuclei (AGN) show evidence of massive outflows of material in a variety of phases including ionized, neutral atomic, and molecular. Molecular outflows in particular have been the focus of recent interest as they may be responsible for removing gas from the galaxy, thereby suppressing star formation. As material is ejected from the cores of galaxies, interactions of the outflowing material with the interstellar medium can accelerate cosmic rays and produce high-energy gamma rays. In this work, we search for gamma-ray emission from a sample of local galaxies known to host molecular outflows using data collected by the {\fermi} Large Area Telescope. We employ a stacking technique in order to search for and characterize the average gamma-ray emission properties of the sample. Gamma-ray emission is detected from the galaxies in our sample at the $4.4 \, \sigma$ level with a power-law photon index of $\Gamma \approx 2$ in the 1-800 GeV energy range. The emission is found to correlate with tracers of star formation activity, namely the $8-1000 \: \mu$m infrared luminosity. We also find that the observed signal can be predominantly attributed to \ion{H}{ii} galaxies hosting energy-driven outflows. While we do not find evidence suggesting that the outflows are accelerating charged particles directly, galaxies with molecular outflows may produce more gamma rays than galaxies without outflows. In particular, the set consisting of gamma-ray-detected galaxies with molecular outflows are nearly perfect calorimeters and may be future targets for searches of high-energy neutrinos.
... First are the relatively slow, ∼100 km s −1 outflows detected through their numerous absorption lines in the soft X-ray spectra of Seyfert galaxies (e.g., Kaastra et al. 2000). Second, are the ultrafast outflows (∼0.1c) detected mostly via highly blueshifted Fe-K lines (Tombesi et al. 2010;Nardini et al. 2015). Third, are the high column density outflows that almost completely obscure the soft X-ray AGN emission (Kaastra et al. 2014a). ...
The physics behind the ionization structure of outflows from black holes is yet to be fully understood. Using archival observations with the Chandra/HETG gratings over the past two decades, we measured an absorption measure distribution for a sample of outflows in nine active galactic nuclei (AGNs), namely the dependence of outflow column density, N H , on the ionization parameter, ξ . The slope of log N H versus log ξ is found to be between 0.00 and 0.72. We find an anticorrelation between the log of total column density of the outflow and the log of AGN luminosity, and none with the black hole mass and accretion efficiency. A major improvement in the diagnostics of AGN outflows will potentially occur with the launch of the XRISM/Resolve spectrometer. We study the ability of Resolve to reveal the outflow ionization structure by constructing the absorption measure distribution from simulated Resolve spectra, utilizing its superior resolution and effective area. Resolve constrains the column density as well as HETG, but with much shorter observations.
We investigate the formation of dense stellar clumps in a suite of high-resolution cosmological zoom-in simulations of a massive, star-forming galaxy at z ∼ 2 under the presence of strong quasar winds. Our simulations include multiphase ISM physics from the Feedback In Realistic Environments (FIRE) project and a novel implementation of hyper-refined accretion disc winds. We show that powerful quasar winds can have a global negative impact on galaxy growth while in the strongest cases triggering the formation of an off-centre clump with stellar mass ${\rm M}_{\star }\sim 10^{7}\, {\rm M}_{\odot }$, effective radius ${\rm R}_{\rm 1/2\, \rm Clump}\sim 20\, {\rm pc}$, and surface density $\Sigma _{\star } \sim 10^{4}\, {\rm M}_{\odot }\, {\rm pc}^{-2}$. The clump progenitor gas cloud is originally not star-forming, but strong ram pressure gradients driven by the quasar winds (orders of magnitude stronger than experienced in the absence of winds) lead to rapid compression and subsequent conversion of gas into stars at densities much higher than the average density of star-forming gas. The AGN-triggered star-forming clump reaches ${\rm SFR} \sim 50\, {\rm M}_{\odot }\, {\rm yr}^{-1}$ and $\Sigma _{\rm SFR} \sim 10^{4}\, {\rm M}_{\odot }\, {\rm yr}^{-1}\, {\rm kpc}^{-2}$, converting most of the progenitor gas cloud into stars in ∼2 Myr, significantly faster than its initial free-fall time and with stellar feedback unable to stop star formation. In contrast, the same gas cloud in the absence of quasar winds forms stars over a much longer period of time (∼35 Myr), at lower densities, and losing spatial coherency. The presence of young, ultra-dense, gravitationally bound stellar clumps in recently quenched galaxies could thus indicate local positive feedback acting alongside the strong negative impact of powerful quasar winds, providing a plausible formation scenario for globular clusters.
Binaries containing a compact object orbiting a supermassive black hole are thought to be precursors of gravitational wave events, but their identification has been extremely challenging. Here, we report quasi-periodic variability in x-ray absorption, which we interpret as quasi-periodic outflows (QPOuts) from a previously low-luminosity active galactic nucleus after an outburst, likely caused by a stellar tidal disruption. We rule out several models based on observed properties and instead show using general relativistic magnetohydrodynamic simulations that QPOuts, separated by roughly 8.3 days, can be explained with an intermediate-mass black hole secondary on a mildly eccentric orbit at a mean distance of about 100 gravitational radii from the primary. Our work suggests that QPOuts could be a new way to identify intermediate/extreme-mass ratio binary candidates.
By using the GRAVITY instrument with the near-infrared (NIR) Very Large Telescope Interferometer (VLTI), the structure of the broad (emission-)line region (BLR) in active galactic nuclei (AGNs) can be spatially resolved, allowing the central black hole (BH) mass to be determined. This work reports new NIR VLTI/GRAVITY interferometric spectra for four type 1 AGNs (Mrk 509, PDS 456, Mrk 1239, and IC 4329A) with resolved broad-line emission. Dynamical modelling of interferometric data constrains the BLR radius and central BH mass measurements for our targets and reveals outflow-dominated BLRs for Mrk 509 and PDS 456. We present an updated radius-luminosity (R-L) relation independent of that derived with reverberation mapping (RM) measurements using all the GRAVITY-observed AGNs. We find our R-L relation to be largely consistent with that derived from RM measurements except at high luminosity, where BLR radii seem to be smaller than predicted. This is consistent with RM-based claims that high Eddington ratio AGNs show consistently smaller BLR sizes. The BH masses of our targets are also consistent with the standard $M_ BH relation. Model-independent photocentre fitting shows spatial offsets between the hot dust continuum and the BLR photocentres (ranging from sim 17 mu as to 140 mu as) that are generally perpendicular to the alignment of the red- and blueshifted BLR photocentres. These offsets are found to be related to the AGN luminosity and could be caused by asymmetric K-band emission of the hot dust, shifting the dust photocentre. We discuss various possible scenarios that can explain this phenomenon.
We analyze a sample of 21 “bare” Seyfert 1 active galactic nuclei, a subclass of Seyfert 1 galaxies, with intrinsic absorption N H ∼ 10 ²⁰ cm ⁻² , in the local Universe ( z < 0.2) using XMM-Newton and Swift/XRT observations. The luminosities of the primary continuum, the X-ray emission in the 3–10 keV energy range, and the soft excess—the excess emission that appears above the low-energy extrapolation of the power-law fit of 3–10 keV X-ray spectra—are calculated. Our spectral analysis reveals that the long-term intrinsic luminosities of the soft excess and the primary continuum are tightly correlated ( L PC ∝ L SE 1.1 ± 0.04 ) . We also found that the luminosities are correlated for each source. This result suggests that both the primary continuum and soft excess emissions exhibit a dependency on the accretion rate in a similar way.
We discuss the origin of a very unusual spectral structure observed in the Fe-K band of the Seyfert galaxy Mrk 1513, a local ( z = 0.063) active galactic nucleus (AGN) that is efficiently accreting matter onto its central supermassive black hole ( L bol / L Edd ∼ 0.5). We consider the highest quality X-ray observation of this source available to date, performed in 2003 by XMM–Newton . The hard X-ray spectrum is characterised by a remarkable spectral drop at ∼7 keV, which can be interpreted as either the onset of a broad absorption trough or the blue wing of a relativistic emission line. Overall, this complex feature is significant at > 5 σ , and it is qualitatively reminiscent of a P Cygni profile. A serendipitous spectrum of lower quality taken by XMM–Newton in 2015 qualitatively confirms the presence of similar Fe-K structures. Although it is not possible to distinguish between the two physical scenarios on sheer statistical grounds with the current data, several considerations lend weight to the possibility that Mrk 1513 is actually hosting a persistent outflow at accretion-disc scales, thus adding to the select number of known AGN in which a wide-angle X-ray wind has been identified so far.
Context. Accretion disk winds launched close to supermassive black holes (SMBHs) are a viable mechanism providing feedback between the SMBH and the host galaxy.
Aims. We aim to characterize the X-ray properties of the inner accretion disk wind of the nearby active galactic nucleus PG 1126-041 and to study its connection with the UV-absorbing wind.
Methods. We performed a spectroscopic analysis of eight XMM-Newton observations of PG 1126-041 taken between 2004 and 2015, using both phenomenological models and the most advanced accretion disk wind models available. For half of the data set, we were able to compare the X-ray analysis results with the results of quasi-simultaneous, high-resolution, spectroscopic UV observations taken with the Cosmic Origins Spectrograph on board the Hubble Space Telescope.
Results. The X-ray spectra of PG 1126-041 are complex and absorbed by ionized material, which is highly variable on multiple timescales, sometimes as short as 11 days. Accretion disk wind models can account for most of the X-ray spectral complexity of PG 1126-041, with the addition of massive clumps, represented by a partially covering absorber. Variations in column density ( N H ∼ 5 − 20 × 10 ²² cm ⁻² ) of the partially covering absorber drive the observed X-ray spectral variability of PG 1126-041. The absorption from the X-ray partially covering gas and from the blueshifted C IV troughs appear to vary in a coordinated way.
Conclusions. The line of sight toward PG 1126-041 offers a privileged view through a highly dynamic nuclear wind originating on inner accretion disk scales, making the source a very promising candidate for future detailed studies of the physics of accretion disk winds around SMBHs.
The imminent launch of XRISM will usher in an era of high-resolution X-ray spectroscopy. For active galactic nuclei (AGN) this is an exciting epoch that is full of massive potential for uncovering the ins and outs of supermassive black hole accretion. In this work, we review AGN research topics that are certain to advance in the coming years with XRISM and prognosticate the possibilities with Athena and Arcus. Specifically, our discussion focuses on: (i) the relatively slow moving ionised winds known as warm absorbers and obscurers; (ii) the iron emitting from different regions of the inner and outer disc, broad line region, and torus; and (iii) the ultrafast outflows that may be the key to understanding AGN feedback.
Recent radiation-magnetohydrodynamic simulations of active galactic nuclei predict the presence of the disk winds, which may become unstable and turn into fragmented clumps far from the central black hole. These inner winds and the outer clumps may be observed as ultrafast outflows (UFOs) and partial absorbers, respectively. However, it is challenging to observationally constrain their origins because of the complicated spectral features and variations. To resolve such degeneracies of the clumpy absorbers and other components, we developed a novel spectral-ratio model fitting technique that estimates the variable absorbing parameters from the ratios of the partially absorbed spectra to the non-absorbed one, canceling the complex non-variable spectral features. We applied this method to the narrow-line Seyfert 1 galaxy IRAS 13224-3809 observed by XMM-Newton in 2016 for ∼1.5 Ms. As a result, we found that the soft spectral variation is mostly caused by changes in the partial covering fraction of the mildly ionized clumpy absorbers, whose outflow velocities are similar to those of the UFO (∼0.2–0.3 c ). Furthermore, the velocities of the clumpy absorbers and UFOs increase similarly with the X-ray fluxes, consistent with the change in the UV-dominant continuum flux. We also discovered a striking correlation between the clump covering fraction and the equivalent width of the UFO absorption lines, which indicates that increasing the outflow in the line of sight leads to more prominent UFOs and more partial absorption. These findings strongly suggest that the clumpy absorbers and the UFO share the same origin, driven by the same UV-dominant continuum radiation.
The Hot Universe Baryon Surveyor (HUBS) is a proposed space-based X-ray telescope for detecting X-ray emissions from the hot gas content in our universe. With its unprecedented spatially-resolved high-resolution spectroscopy and large field of view, the HUBS mission will be uniquely qualified to measure the physical and chemical properties of the hot gas in the interstellar medium, the circumgalactic medium, the intergalactic medium, and the intracluster medium. These measurements will be valuable for two key scientific goals of HUBS, namely to unravel the AGN and stellar feedback physics that governs the formation and evolution of galaxies, and to probe the baryon budget and multi-phase states from galactic to cosmological scales. In addition to these two goals, the HUBS mission will also help us solve some problems in the fields of galaxy clusters, AGNs, diffuse X-ray backgrounds, supernova remnants, and compact objects. This paper discusses the perspective of advancing these fields using the HUBS telescope.
We present the analysis of the rest frame ultraviolet and optical spectra of 30 bright blue quasars at z ∼ 3, selected to examine the suitability of active galactic nuclei as cosmological probes. In our previous works, based on pointed XMM-Newton observations, we found an unexpectedly high fraction (≈25%) of X-ray weak quasars in the sample. The latter sources also display a flatter UV continuum and a broader and fainter C IV profile in the archival UV data with respect to their X-ray normal counterparts. Here we present new observations with the Large Binocular Telescope in both the zJ (covering the rest frame ≃2300–3100 Å) and the K S (≃4750–5350 Å) bands. We estimated black hole masses ( M BH ) and Eddington ratios ( λ Edd ) from the available rest frame optical and UV emission lines (H β , Mg II ), finding that our z ∼ 3 quasars are on average highly accreting (⟨ λ Edd ⟩≃1.2 and ⟨ M BH ⟩≃10 9.7 M ⊙ ), with no difference in λ Edd or M BH between X-ray weak and X-ray normal quasars. From the zJ spectra, we derived the properties (e.g. flux, equivalent width) of the main emission lines (Mg II , Fe II ), finding that X-ray weak quasars display higher Fe II /Mg II ratios with respect to typical quasars. Fe II /Mg II ratios of X-ray normal quasars are instead consistent with other estimates up to z ≃ 6.5, corroborating the idea of already chemically mature broad line regions at early cosmic time. From the K S spectra, we find that all the X-ray weak quasars present generally weaker [O III ] emission (EW < 10 Å) than the normal ones. The sample as a whole, however, abides by the known X-ray-[O III ] luminosity correlation, hence the different [O III ] properties are likely due to an intrinsically weaker [O III ] emission in X-ray weak objects, associated to the shape of the spectral energy distribution. We interpret these results in the framework of accretion-disc winds.
Galaxy-wide outflows driven by active galactic nuclei (AGN) are an important ingredient in galaxy evolution. Analytical calculations suggest that such outflows have significant inertia and can persist long after the AGN itself fades away. We use hydrodynamical simulations of outflows in idealised galaxy bulges to investigate the propagation of these ‘fossil’ AGN outflows. We find that fossil outflows should be common in gas-poor galaxies but form only rarely in gas-rich ones; in general, fossil outflows should outnumber driven ones by a factor of a few in the local Universe, and possibly more at high redshift. When they do form, fossil outflows tend to be lopsided and detached from the nucleus, and colder than their driven counterparts, with a more prominent molecular phase. Spatially resolved and/or multiphase observations can help distinguish fossil AGN outflows from star formation-driven ones, which have similar integrated properties. We discuss a number of spatially-resolved observations of outflows, suggesting that most show evidence of fossil outflow existence, sometimes together with driven outflows on smaller scales.
Ultrafast outflows (UFOs) have been revealed in a large number of active galactic nuclei (AGN) and are regarded as promising candidates for AGN feedback on the host galaxy. The nature and launching mechanism of UFOs are not yet fully understood. Here we perform a time- and flux-resolved X-ray spectroscopy on four XMM–Newton observations of a highly accreting narrow-line Seyfert 1 (NLS1) galaxy, Mrk 1044, to study the dependence of the outflow properties on the source luminosity. We find that the UFO in Mrk 1044 responds to the source variability quickly and its velocity increases with the X-ray flux, suggesting a high-density ($10^{9}\!-\!4.5\times 10^{12}\, \mathrm{cm}^{-3}$) and radiatively driven outflow, launched from the region within a distance of $98\!-\!6600\, R_\mathrm{g}$ from the black hole. The kinetic energy of the UFO is conservatively estimated ($L_\mathrm{UFO}\sim 4.4~{{\ \rm per\ cent}}\, L_\mathrm{Edd}$), reaching the theoretical criterion to affect the evolution of the host galaxy. We also find that emission lines, from a large-scale region, have a blueshift of 2700–4500 km s−1 in the spectra of Mrk 1044, which is rarely observed in AGN. By comparing with other sources, we propose a correlation between the blueshift of emission lines and the source accretion rate, which can be verified by a future sample study.
The bulk of X‐ray spectroscopic studies of active galactic nuclei (AGN) are focused on local () sources with low‐to‐moderate (<0.3) Eddington ratio (). It is then mandatory to overcome this limitation and improve our understanding of highly accreting AGN. In this work, we present the preliminary results from the analysis of a sample of high‐ radio‐quiet AGN at , based on the 10th release of the XMM‐Newton serendipitous source catalog, that we named as XMM‐Newton High‐Eddington Serendipitous AGN Sample (X‐HESS). Almost of the X‐HESS AGN have multi‐epoch archival observations and of the sources can rely on simultaneous OM optical data. First results reveal sources showing signatures of ultra‐fast outflows and remarkable long‐ and short‐term X‐ray flux variations. Indeed in SDSS J095847.88+690532.7 (), one of the most densely monitored objects hosting a supermassive black hole, we discovered a variation of the soft X‐ray flux by a factor of >2 over approximately one week (rest‐frame). Large variations in the power‐law continuum photon index are also observed, questioning expectations from previously reported relations, for which would be a ubiquitous hallmark of AGN with .
Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, although direct observational evidence is still scarce and debated. Here we present Early Release Science JWST NIRSpec IFU observations of the z = 1.59 prototypical obscured Active Galactic Nucleus (AGN) XID2028: This target represents a unique test case for studying quasar feedback at the peak epoch of AGN-galaxy co-evolution because extensive multi-wavelength coverage is available and a massive and extended outflow is detected in the ionised and molecular components. With the unprecedented sensitivity and spatial resolution of the JWST, the NIRSpec dataset reveals a wealth of structures in the ionised gas kinematics and morphology that were previously hidden in the seeing-limited ground-based data. In particular, we find evidence of an interaction between the interstellar medium of the galaxy and the quasar-driven outflow and radio jet that produces an expanding bubble from which the fast and extended wind detected in previous observations emerges. The new observations confirm the complex interplay between the AGN jet, wind and the interstellar medium of the host galaxy, highlighting the role of low-luminosity radio jets in AGN feedback. They also clearly show the new window that NIRSpec opens for detailed studies of feedback at high redshift.
We present Atacama Large Millimetre/submillimetre Array (ALMA) CO(1–0) observations of the nearby infrared luminous (LIRG) galaxy pair IRAS 05054+1718 (also known as CGCG 468-002), as well as a new analysis of X-ray data of this source collected between 2012 and 2021 using the Nuclear Spectroscopic Telescope Array ( NuSTAR ), Swift , and the XMM-Newton satellites. The western component of the pair, NED01, hosts a Seyfert 1.9 nucleus that is responsible for launching a powerful X-ray ultra-fast outflow (UFO). Our X-ray spectral analysis suggests that the UFO could be variable or multi-component in velocity, ranging from v / c ∼ −0.12 (as seen in Swift ) to v / c ∼ −0.23 (as seen in NuSTAR ), and constrains its momentum flux to be ṗ out X−ray ∼ (4 ± 2) × 10 ³⁴ g cm s ⁻² . The ALMA CO(1–0) observations, obtained with an angular resolution of 2.2″, although targeting mainly NED01, also include the eastern component of the pair, NED02, a less-studied LIRG with no clear evidence of an active galactic nucleus (AGN). We study the CO(1–0) kinematics in the two galaxies using the 3D-BAROLO code. In both sources we can model the bulk of the CO(1–0) emission with rotating disks and, after subtracting the best-fit models, we detect compact residual emission at S / N = 15 within ∼3 kpc of the centre. A molecular outflow in NED01, if present, cannot be brighter than such residuals, implying an upper limit on its outflow rate of Ṁ out mol ≲ 19 ± 14 M ⊙ yr ⁻¹ and on its momentum rate of ṗ out mol ≲ (2.7 ± 2.4) × 10 ³⁴ g cm s ⁻¹ . Combined with the revised energetics of the X-ray wind, we derive an upper limit on the momentum rate ratio of ṗ out mol / ṗ out X−ray < 0.67. We discuss these results in the context of the expectations of AGN feedback models, and we propose that the X-ray disk wind in NED01 has not significantly impacted the molecular gas reservoir (yet), and we can constrain its effect to be much smaller than expectations of AGN ‘energy-driven’ feedback models. We also consider and discuss the hypothesis of asymmetries of the molecular disk not properly captured by the 3D-BAROLO code. Our results highlight the challenges in testing the predictions of popular AGN disk-wind feedback theories, even in the presence of good-quality multi-wavelength observations.
Context. Obscuration events in type I active galactic nuclei (AGN) have been detected more frequently in recent years. The strong flux decrease in the soft X-ray band between observations has been caused by clouds with large column densities transiting our line of sight (LOS) and covering the central AGN. Another event has been captured in NGC 3227 at the end of 2019, which was observed with XMM-Newton , NuSTAR , and the Hubble Space Telescope.
Aims. We aim to determine the nature and origin of the observed spectral variability in the 2019 obscuration event.
Methods. We study the evolution of the obscurer by splitting the two XMM-Newton observations from 2019 into timing bins of length ∼10 ks. We used the SPEX code to analyse the 0.35–10 keV EPIC-PN spectra of each timing bin.
Results. In the first observation (Obs 1), there is a strong anti-correlation between the column density ( N H ) of the obscurer and the continuum normalisations of the X-ray power law and soft Comptonisation components ( N pow and N comt , respectively). The power-law continuum models the hard X-rays produced by the corona, and the Comptonisation component models the soft X-ray excess and emission from the accretion disk. Through further testing, we conclude that the continuum is likely to drive the observed variability, but we cannot rule out a possible contribution from N H of the obscurer if it fully transverses across the ionising source within our LOS during the observation. The ionisation parameter ( ξ ) of the obscurer is not easily constrained, and therefore it is not clear whether it varies in response to changes in the ionising continuum. The second observation (Obs 2) displays a significantly lower count rate due to the combination of a high N H and covering fraction of the obscurer, and a lower continuum flux.
Conclusions. The observed variability seen during the obscuration event of NGC 3227 in 2019 is likely driven by the continuum, but the obscurer varies at the same time, making it difficult to distinguish between the two possibilities with full certainty.
The presence of an obscuring torus at parsec-scale distances from the central black hole is the main ingredient for the Unified Model of active galactic nuclei (AGN), as obscured sources are thought to be seen through this structure. However, the Unified Model fails to describe a class of sources that undergo dramatic spectral changes, transitioning from obscured to unobscured and vice versa through time. The variability in these sources, which are known as changing-look AGN (CLAGN), is thought to be produced by a clumpy medium at much smaller distances than the conventional obscuring torus. ESO 323-G77 is a CLAGN that was observed in various states through the years with Chandra , Suzaku, Swift -XRT, and XMM-Newton , from unobscured ( N H < 3 × 10 ²² cm ⁻² ) to Compton-thin ( N H ∼ 1 − 6 × 10 ²³ cm ⁻² ) and even Compton-thick ( N H > 1 × 10 ²⁴ cm ⁻² ), on timescales as short as one month. We present an analysis of the first NuSTAR monitoring of ESO 323-G77, consisting of five observations taken at different timescales (1, 2, 4, and 8 weeks from the first one) in 2016–2017, in which the AGN was caught in a persistent Compton-thin obscured state ( N H ∼ 2 − 4 × 10 ²³ cm ⁻² ). We find that a Compton-thick reflector is present ( N H, refl = 5 × 10 ²⁴ cm ⁻² ), most likely associated with the presence of the putative torus. Two ionized absorbers are unequivocally present, located within maximum radii of r max, 1 = 1.5 pc and r max, 2 = 0.01 pc. In one of the observations, the inner ionized absorber is blueshifted, indicating the presence of a possible faster ( v out = 0.2 c ) ionized absorber, marginally detected at 3 σ . Finally, we are able to constrain the coronal temperature and the optical depth of ESO 323-G77, obtaining kT e = 38 keV or kT e = 36 keV, and τ = 1.4 or τ = 2.8, depending on the coronal geometry assumed.
Radiation‐magnetohydrodynamic simulation of the active galactic nuclei predicts the presence of the strong accretion disk wind, which gets unstable far from the central region and turns into gas clumps. These inner wind and outer clumps may be actually observed as the ultrafast outflows (UFOs) and the clumpy absorbers, respectively. We call this picture as the “hot inner and clumpy outer wind model.” Observationally, it is challenging to place constraints on the origin of the UFOs and clumpy absorbers due to complicated spectral variations. We developed a novel method, “spectral‐ratio model fitting,” to resolve parameter degeneracy of the clumpy absorbers and other spectral components. In this method, the parameters of the absorber in the line of sight are estimated from the ratio of the partially absorbed spectrum to the non‐absorbed one. We applied this method to the narrow‐line Seyfert 1 galaxy IRAS 13224–3809 observed by XMM‐Newton in 2016 for 1.5 Ms, where the source showed extreme spectral variability and complex absorption features. As a result, we found that the soft spectral variation is mostly explained by a change in the covering fraction of the mildly‐ionized clumpy absorbers, and that these absorbers are outflowing with such a high velocity that is comparable to that of the UFO (∼0.2–0.3 c).
We present a new X-ray spectroscopic study of 22 luminous (2 × 10 ⁴⁵ ≲ L bol /erg s ⁻¹ ≲ 2 × 10 ⁴⁶ ) active galactic nuclei (AGNs) at intermediate redshifts (0.1 ≲ z ≲ 0.4), as part of the SUpermassive Black hole Winds in the x-rAYS (SUBWAYS) sample, mostly composed of quasars and type 1 AGNs. Here, 17 targets were observed with XMM-Newton in 2019–2020, and the remaining 5 are from previous observations. The aim of this large campaign (1.45 Ms duration) is to characterise the various manifestations of winds in the X-rays driven from supermassive black holes in AGNs. In this paper we focus on the search for and characterisation of ultra-fast outflows (UFOs), which are typically detected through blueshifted absorption troughs in the Fe K band ( E > 7 keV). By following Monte Carlo procedures, we confirm the detection of absorption lines corresponding to highly ionised iron (e.g. Fe XXV H α and Fe XXVI Ly α ) in 7 out of 22 sources at the ≳95% confidence level (for each individual line). The global combined probability of such absorption features in the sample is > 99.9%. The SUBWAYS campaign, based on XMM-Newton , extends to higher luminosities and redshifts than previous local studies on Seyferts. We find a UFO detection fraction of ∼30% of the total sample, which is in agreement with previous findings. This work independently provides further support for the existence of highly ionised matter propagating at mildly relativistic speeds (≳0.1 c ) in a considerable fraction of AGNs over a broad range of luminosities, which is believed to play a key role in the self-regulated AGN feeding-feedback cycle, as also supported by hydrodynamical multi-phase simulations.
Narrow-Line Seyfert 1 (NLS1) Galaxies are an important type of active galactic nucleus (AGN), generally expected to be accreting at high Eddington rate. The properties of their outflows and importance of AGN feedback remain intriguing. We report on the discovery of fast outflowing warm absorbers (WAs) in the NLS1 PG 1001+054, with velocities in the range of 7000 to 9000 kilometers per second. They are identified with blueshifted Lyman alpha, N v and Si iv lines in the high resolution ultraviolet (UV) spectra taken with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST). We perform photoionization modeling using XSTAR with three WAs. The derived physical properties are typical of WAs in terms of ionization and column density, whereas the outflow velocities are significantly higher. The estimated location of these WAs ranges from 1 to 73 parsecs away from the AGN. Together with previous detection of high ionization absorber in the X-ray for PG 1001+054, we suggest that the fast outflowing UV absorber is probably a part of a multiphase outflow. Such structure is likely produced by the outflow launched from AGN at accretion disk scale, which shocks the ambient ISM producing stratified absorbers. Assuming contribution from the three WAs at tens of parsecs, the estimated ratio between the kinetic power of the outflow and AGN Eddington luminosity could reach 1.7 percent, raising the possibility of sufficient influence on the host galaxy when compared to some theoretical models for efficient AGN feedback.
Aims. IRAS 23226-3843 has previously been classified as a changing-look active galactic nucleus (AGN) based on observations taken in the 1990s in comparison to X-ray data ( Swift , XMM-Newton , and NuSTAR ) and optical spectra taken after a very strong X-ray decline in 2017. In 2019, Swift observations revealed a strong rebrightening in X-ray and UV fluxes. We aimed to study this outburst in greater detail.
Methods. We took follow-up Swift , XMM-Newton , and NuSTAR observations of IRAS 23226-3843 together with optical spectra (SALT and SAAO 1.9 m telescope) from 2019 until 2021.
Results. IRAS 23226-3843 showed a strong X-ray and optical outburst in 2019. It varied in the X-ray continuum by a factor of 5 and in the optical continuum by a factor of 1.6 within two months. This corresponds to a factor of 3 after correction for the host galaxy contribution. The Balmer and Fe II emission-line intensities showed comparable variability amplitudes during the outburst in 2019. The H α emission-line profiles of IRAS 23226-3843 changed from a blue-peaked profile in the years 1997 and 1999 to a broad double-peaked profile in 2017 and 2019. However, there were no major profile variations in the extremely broad double-peaked profiles despite the strong intensity variations in 2019. One year after the outburst, IRAS 23226-3843 changed its optical spectral type and became a Seyfert type 2 object in 2020. Blue outflow components are present in the optical Balmer lines and in the Fe band in the X-rays. A deep broadband XMM-Newton / NuSTAR spectrum was taken during IRAS 23226-3843’s maximum state in 2019. This spectrum is qualitatively very similar to a spectrum taken in 2017, but by a factor of 10 higher. The soft X-ray band appears featureless. The soft excess is well modeled with a Comptonization model. A broadband fit with a power-law continuum, Comptonized soft excess, and Galactic absorption gives a good fit to the combined EPIC-pn and NuSTAR spectrum. In addition, we see a complex and broadened Fe K emission-line profile in the X-rays. The changing-look character in IRAS 23226-3843 is most probably caused by changes in the accretion rate – based on the short-term variations on timescales of weeks to months.
We present a UV spectroscopic study of ionized outflows in 21 active galactic nuclei (AGN), observed with the Hubble Space Telescope (HST). The targets of the Supermassive Black Hole Winds in X-rays (SUBWAYS) sample were selected with the aim to probe the parameter space of the underexplored AGN between the local Seyfert galaxies and the luminous quasars at high redshifts. Our targets, spanning redshifts of 0.1–0.4 and bolometric luminosities ( L bol ) of 10 ⁴⁵ –10 ⁴⁶ erg s ⁻¹ , have been observed with a large multi-wavelength campaign using XMM-Newton , NuSTAR , and HST. Here, we model the UV spectra and look for different types of AGN outflows that may produce either narrow or broad UV absorption features. We examine the relations between the observed UV outflows and other properties of the AGN. We find that 60% of our targets show a presence of outflowing H I absorption, while 40% exhibit ionized outflows seen as absorption by either C IV , N V , or O VI . This is comparable to the occurrence of ionized outflows seen in the local Seyfert galaxies. All UV absorption lines in the sample are relatively narrow, with outflow velocities reaching up to −3300 km s ⁻¹ . We did not detect any UV counterparts to the X-ray ultra-fast outflows (UFOs), most likely due to their being too highly ionized to produce significant UV absorption. However, all SUBWAYS targets with an X-ray UFO that have HST data demonstrate the presence of UV outflows at lower velocities. We find significant correlations between the column density ( N ) of the UV ions and L bol of the AGN, with N H I decreasing with L bol , while N O VI is increasing with L bol . This is likely to be a photoionization effect, where toward higher AGN luminosities, the wind becomes more ionized, resulting in less absorption by neutral or low-ionization ions and more absorption by high-ionization ions. In addition, we find that N of the UV ions decreases as their outflow velocity increases. This may be explained by a mechanical power that is evacuating the UV-absorbing medium. Our observed relations are consistent with multiphase AGN feeding and feedback simulations indicating that a combination of both radiative and mechanical processes are in play.
This work focuses on active galactic nuclei (AGNs) and on the relation between the sizes of the hot dust continuum and the broad-line region (BLR). We find that the continuum size measured using optical/near-infrared interferometry (OI) is roughly twice that measured by reverberation mapping (RM). Both OI and RM continuum sizes show a tight relation with the H β BLR size, with only an intrinsic scatter of 0.25 dex. The masses of supermassive black holes (BHs) can hence simply be derived from a dust size in combination with a broad line width and virial factor. Since the primary uncertainty of these BH masses comes from the virial factor, the accuracy of the continuum-based BH masses is close to those based on the RM measurement of the broad emission line. Moreover, the necessary continuum measurements can be obtained on a much shorter timescale than those required monitoring for RM, and they are also more time efficient than those needed to resolve the BLR with OI. The primary goal of this work is to demonstrate a measuring of the BH mass based on the dust-continuum size with our first calibration of the R BLR – R d relation. The current limitation and caveats are discussed in detail. Future GRAVITY observations are expected to improve the continuum-based method and have the potential of measuring BH masses for a large sample of AGNs in the low-redshift Universe.
Supermassive black holes in the nuclei of active galaxies expel large amounts
of matter through powerful winds of ionized gas. The archetypal active galaxy
NGC 5548 has been studied for decades, and high-resolution X-ray and UV
observations have previously shown a persistent ionized outflow. An observing
campaign in 2013 with six space observatories shows the nucleus to be obscured
by a long-lasting, clumpy stream of ionized gas never seen before. It blocks
90% of the soft X-ray emission and causes simultaneous deep, broad UV
absorption troughs. The outflow velocities of this gas are up to five times
faster than those in the persistent outflow, and at a distance of only a few
light days from the nucleus, it may likely originate from the accretion disk.
We present evidence for the rapid variability of the high-velocity iron K-shell absorption in the nearby (z = 0.184) quasar PDS 456. From a recent long Suzaku observation in 2013 (~1 Ms effective duration), we find that the equivalent width of iron K absorption increases by a factor of ~5 during the observation, increasing from <105 eV within the first 100 ks of the observation, toward a maximum depth of ~500 eV near the end. The implied outflow velocity of ~0.25 c is consistent with that claimed from earlier (2007, 2011) Suzaku observations. The absorption varies on timescales as short as ~1 week. We show that this variability can be equally well attributed to either (1) an increase in column density, plausibly associated with a clumpy time-variable outflow, or (2) the decreasing ionization of a smooth homogeneous outflow which is in photo-ionization equilibrium with the local photon field. The variability allows a direct measure of absorber location, which is constrained to within r = 200-3500 r
g of the black hole. Even in the most conservative case, the kinetic power of the outflow is 6% of the Eddington luminosity, with a mass outflow rate in excess of ~40% of the Eddington accretion rate. The wind momentum rate is directly equivalent to the Eddington momentum rate which suggests that the flow may have been accelerated by continuum scattering during an episode of Eddington-limited accretion.
X-ray reflection models are used to constrain the properties of the accretion
disk, such as the degree of ionization of the gas and the elemental abundances.
In combination with general relativistic ray tracing codes, additional
parameters like the spin of the black hole and the inclination to the system
can be determined. However, current reflection models used for such studies
only provide angle-averaged solutions for the flux reflected at the surface of
the disk. Moreover, the emission angle of the photons changes over the disk due
to relativistic light bending. To overcome this simplification, we have
constructed the new angle-dependent reflection model RELXILL, by
self-consistently connecting the XILLVER reflection models with the
relativistic blurring code RELLINE.
We study the properties of massive, galactic-scale outflows of molecular gas
and investigate their impact on galaxy evolution. We present new IRAM PdBI
CO(1-0) observations of local ULIRGs and QSO hosts: clear signature of massive
and energetic molecular outflows, extending on kpc scales, is found in the
CO(1-0) kinematics of four out of seven sources, with measured outflow rates of
several 100 Msun/yr. We combine these new observations with data from the
literature, and explore the nature and origin of massive molecular outflows
within an extended sample of 19 local galaxies. We find that
starburst-dominated galaxies have an outflow rate comparable to their SFR, or
even higher by a factor of ~ 2-4, implying that starbursts can indeed be
effective in removing cold gas from galaxies. Nevertheless, our results suggest
that the presence of an AGN can boost the outflow rate by a large factor, which
is found to increase with the L_AGN/L_bol ratio. The gas depletion time-scales
due to molecular outflows are anti-correlated with the presence and luminosity
of an AGN in these galaxies, and range from a few hundred million years in
starburst galaxies, down to just a few million years in galaxies hosting
powerful AGNs. In quasar hosts the depletion time-scales due to the outflow are
much shorter than the depletion time-scales due to star formation. We estimate
the outflow kinetic power and find that, for galaxies hosting powerful AGNs, it
corresponds to about 5% of the AGN luminosity, as expected by models of AGN
feedback. Moreover, we find that momentum rates of about 20 L_AGN/c are common
among the AGN-dominated sources in our sample. For "pure" starburst galaxies
our data tentatively support models in which outflows are mostly
momentum-driven by the radiation pressure from young stars onto dusty clouds.
We present a comparison of two Suzaku X-ray observations of the nearby
(z=0.184), luminous ($L_{bol} \sim 10^{47}$ erg s$^{-1}$) type I quasar,
PDS456. A new 125ks Suzaku observation in 2011 caught the quasar during a
period of low X-ray flux and with a hard X-ray spectrum, in contrast to a
previous 190ks Suzaku observation in 2007 when the quasar appeared brighter and
had a steep ($\Gamma>2$) X-ray spectrum. The 2011 X-ray spectrum contains a
pronounced trough near 9\,keV in the quasar rest frame, which can be modeled
with blue-shifted iron K-shell absorption, most likely from the He and H-like
transitions of iron. The absorption trough is observed at a similar rest-frame
energy as in the earlier 2007 observation, which appears to confirm the
existence of a persistent high velocity wind in PDS 456, at an outflow velocity
of $0.25-0.30$c. The spectral variability between 2007 and 2011 can be
accounted for by variations in a partial covering absorber, increasing in
covering fraction from the brighter 2007 observation to the hard and faint 2011
observation. Overall the low flux 2011 observation can be explained if PDS 456
is observed at relatively low inclination angles through a Compton thick wind,
originating from the accretion disk, which significantly attenuates the X-ray
flux from the quasar.
In some radio-quiet active galaxies (AGN), high-energy absorption features in
the x-ray spectra have been interpreted as Ultrafast Outflows (UFOs) -- highly
ionised material (e.g. Fe XXV and Fe XXVI) ejected at mildly relativistic
velocities. In some cases, these outflows can carry energy in excess of the
binding energy of the host galaxy. Needless to say, these features demand our
attention as they are strong signatures of AGN feedback and will influence
galaxy evolution. For the same reason, alternative models need to be discussed
and refuted or confirmed. Gallo & Fabian proposed that some of these features
could arise from resonance absorption of the reflected spectrum in a layer of
ionised material located above and corotating with the accretion disc.
Therefore, the absorbing medium would be subjected to similar blurring effects
as seen in the disc. A priori, the existence of such plasma above the disc is
as plausible as a fast wind. In this work, we highlight the ambiguity by
demonstrating that the absorption model can describe the ~7.6 keV absorption
feature (and possibly other features) in the quasar PG 1211+143, an AGN that is
often described as a classic example of an UFO. In this model, the 2-10 keV
spectrum would be largely reflection dominated (as opposed to power law
dominated in the wind models) and the resonance absorption would be originating
in a layer between about 6 and 60 gravitational radii. The studies of such
features constitutes a cornerstone for future X-ray observatories like Astro-H
and Athena+. Should our model prove correct, or at least important in some
cases, then absorption will provide another diagnostic tool with which to probe
the inner accretion flow with future missions.
We review the observed demographics and inferred evolution of supermassive
black holes (BHs) found by dynamical modeling of spatially resolved kinematics.
Most influential was the discovery of a tight correlation between BH mass and
the velocity dispersion of the host-galaxy bulge. It and other correlations led
to the belief that BHs and bulges coevolve by regulating each other's growth.
New results are now replacing this simple story with a richer and more
plausible picture in which BHs correlate differently with different galaxy
components. BHs are found in pure-disk galaxies, so classical
(elliptical-galaxy-like) bulges are not necessary to grow BHs. But BHs do not
correlate with galaxy disks. And any correlations with disk-grown pseudobulges
or halo dark matter are so weak as to imply no close coevolution. We suggest
that there are four regimes of BH feedback. 1- Local, stochastic feeding of
small BHs in mainly bulgeless galaxies involves too little energy to result in
coevolution. 2- Global feeding in major, wet galaxy mergers grows giant BHs in
short, quasar-like "AGN" events whose feedback does affect galaxies. This makes
classical bulges and coreless-rotating ellipticals. 3- At the highest BH
masses, maintenance-mode feedback into X-ray gas has the negative effect of
helping to keep baryons locked up in hot gas. This happens in giant,
core-nonrotating ellipticals. They inherit coevolution magic from smaller
progenitors. 4- Independent of any feedback physics, the averaging that results
from successive mergers helps to engineer tight BH correlations.
We present a new and complete library of synthetic spectra for modeling the component of emission that is reflected from an illuminated accretion disk. The spectra were computed using an updated version of our code XILLVER that incorporates new routines and a richer atomic database. We offer in the form of a table model an extensive grid of reflection models that cover a wide range of parameters. Each individual model is characterized by the photon index Γ of the illuminating radiation, the ionization parameter ξ at the surface of the disk (i.e., the ratio of the X-ray flux to the gas density), and the iron abundance A
Fe relative to the solar value. The ranges of the parameters covered are 1.2 ≤ Γ ≤ 3.4, 1 ≤ ξ ≤ 104, and 0.5 ≤ A
Fe ≤ 10. These ranges capture the physical conditions typically inferred from observations of active galactic nuclei, and also stellar-mass black holes in the hard state. This library is intended for use when the thermal disk flux is faint compared to the incident power-law flux. The models are expected to provide an accurate description of the Fe K emission line, which is the crucial spectral feature used to measure black hole spin. A total of 720 reflection spectra are provided in a single FITS file (http://hea-www.cfa.harvard.edu/~javier/xillver/) suitable for the analysis of X-ray observations via the atable model in XSPEC. Detailed comparisons with previous reflection models illustrate the improvements incorporated in this version of XILLVER.
We present an updated and revised analysis of the relationship between the
Hbeta broad-line region (BLR) radius and the luminosity of the active galactic
nucleus (AGN). Specifically, we have carried out two-dimensional surface
brightness decompositions of the host galaxies of 9 new AGNs imaged with the
Hubble Space Telescope Wide Field Camera 3. The surface brightness
decompositions allow us to create "AGN-free" images of the galaxies, from which
we measure the starlight contribution to the optical luminosity measured
through the ground-based spectroscopic aperture. We also incorporate 20 new
reverberation-mapping measurements of the Hbeta time lag, which is assumed to
yield the average Hbeta BLR radius. The final sample includes 41 AGNs covering
four orders of magnitude in luminosity. The additions and updates incorporated
here primarily affect the low-luminosity end of the R-L relationship. The best
fit to the relationship using a Bayesian analysis finds a slope of alpha =
0.533 (+0.035/-0.033), consistent with previous work and with simple
photoionization arguments. Only two AGNs appear to be outliers from the
relationship, but both of them have monitoring light curves that raise doubt
regarding the accuracy of their reported time lags. The scatter around the
relationship is found to be 0.19(+/-0.02) dex, but would be decreased to 0.13
dex by the removal of these two suspect measurements. A large fraction of the
remaining scatter in the relationship is likely due to the inaccurate distances
to the AGN host galaxies. Our results help support the possibility that the R-L
relationship could potentially be used to turn the BLRs of AGNs into
standardizable candles. This would allow the cosmological expansion of the
Universe to be probed by a separate population of objects, and over a larger
range of redshifts.
The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 13
June 2012, is the first focusing high-energy X-ray telescope in orbit. NuSTAR
operates in the band from 3 -- 79 keV, extending the sensitivity of focusing
far beyond the ~10 keV high-energy cutoff achieved by all previous X-ray
satellites. The inherently low-background associated with concentrating the
X-ray light enables NuSTAR to probe the hard X-ray sky with a more than
one-hundred-fold improvement in sensitivity over the collimated or coded-mask
instruments that have operated in this bandpass. Using its unprecedented
combination of sensitivity, spatial and spectral resolution, NuSTAR will pursue
five primary scientific objectives, and will also undertake a broad program of
targeted observations. The observatory consists of two co-aligned
grazing-incidence X-ray telescopes pointed at celestial targets by a three-axis
stabilized spacecraft. Deployed into a 600 km, near-circular, 6degree
inclination orbit, the Observatory has now completed commissioning, and is
performing consistent with pre-launch expectations. NuSTAR is now executing its
primary science mission, and with an expected orbit lifetime of ten years, we
anticipate proposing a guest investigator program, to begin in Fall 2014.
X-ray irradiation of the accretion disc leads to strong reflection features,
which are then broadened and distorted by relativistic effects. We present a
detailed, general relativistic approach to model this irradiation for different
geometries of the primary X-ray source. These geometries include the standard
point source on the rotational axis as well as more jet-like sources, which are
radially elongated and accelerating. Incorporating this code in the relline
model for relativistic line emission, the line shape for any configuration can
be predicted. We study how different irradiation geometries affect the
determination of the spin of the black hole. Broad emission lines are produced
only for compact irradiating sources situated close to the black hole. This is
the only case where the black hole spin can be unambiguously determined. In all
other cases the line shape is narrower, which could either be explained by a
low spin or an elongated source. We conclude that for all those cases and
independent of the quality of the data, no unique solution for the spin exists
and therefore only a lower limit of the spin value can be given.
The XMM-Newton Observatory is a cornerstone mission of the European
Space Agency's Horizon 2000 programme, and is the largest scientific
satellite it has launched to date. This paper summarises the principal
characteristics of the Observatory which are pertinent to scientific
operations. The scientific results appearing in this issue have been
enabled by the unprecedentedly large effective area of the three mirror
modules, which are briefly described. The in-orbit performance and
preliminary calibrations of the observatory are briefly summarised. The
observations from the XMM-Newton calibration and performance
verification phase, which are public and from which most papers in this
issue have been derived, are listed. The flow of data from the
spacecraft, through the ground segment, to the production of preliminary
science products supplied to users is also discussed. Based on
observations obtained with XMM-Newton, an ESA science mission with
instruments and contributions directly funded by ESA Member States and
the USA (NASA).
A new method for calculating line profiles formed in spherically
symmetric stellar winds in which the velocity increases monotonically
outward is described. The source function is calculated with the escape
probability method, but the transfer equation is solved exactly. The
method allows the calculation of singlets and doublets with underlying
photospheric absorption components. Profile comparisons show that the
presented method often attains the same accuracy as profiles calculated
with the comoving frame method but has the advantages of the escape
probability method. It can be run on a small computer and requires
little CPU time, so that it can be used in an interactive analysis of
observed line profiles.
We have reanalyzed the 900 ks Chandra X-ray spectrum of NGC 3783, finding evidence on the asymmetry of the spectral absorption lines. The lines are fitted with a parametric expression that results from an analytical treatment of radiatively driven winds. The line asymmetry distribution derived from the spectrum is consistent with a nonspherical outflow with a finite optical depth. Within this scenario, our model explains the observed correlations between the line velocity shifts and the ionization parameter and between the line velocity shift and the line asymmetry. The present results may provide a framework for detailed testing of models for the dynamics and physical properties of warm absorbers in Seyfert galaxies.
We describe a correlation between the mass Mbh of a galaxy's central black hole and the luminosity-weighted line-of-sight velocity dispersion σe within the half-light radius. The result is based on a sample of 26 galaxies, including 13 galaxies with new determinations of black hole masses from Hubble Space Telescope measurements of stellar kinematics. The best-fit correlation is Mbh = 1.2(±0.2) × 108 M☉(σe/200 km s-1)3.75 (±0.3) over almost 3 orders of magnitude in Mbh; the scatter in Mbh at fixed σe is only 0.30 dex, and most of this is due to observational errors. The Mbh-σe relation is of interest not only for its strong predictive power but also because it implies that central black hole mass is constrained by and closely related to properties of the host galaxy's bulge.
Observations of nearby galaxies reveal a strong correlation between the mass of the central dark object MBH and the velocity dispersion σ of the host galaxy, of the form log(MBH/M☉) = α + β log(σ/σ0); however, published estimates of the slope β span a wide range (3.75-5.3). Merritt & Ferrarese have argued that low slopes (4) arise because of neglect of random measurement errors in the dispersions and an incorrect choice for the dispersion of the Milky Way Galaxy. We show that these explanations and several others account for at most a small part of the slope range. Instead, the range of slopes arises mostly because of systematic differences in the velocity dispersions used by different groups for the same galaxies. The origin of these differences remains unclear, but we suggest that one significant component of the difference results from Ferrarese & Merritt's extrapolation of central velocity dispersions to re/8 (re is the effective radius) using an empirical formula. Another component may arise from dispersion-dependent systematic errors in the measurements. A new determination of the slope using 31 galaxies yields β = 4.02 ± 0.32, α = 8.13 ± 0.06 for σ0 = 200 km s-1. The MBH-σ relation has an intrinsic dispersion in log MBH that is no larger than 0.25-0.3 dex and may be smaller if observational errors have been underestimated. In an appendix, we present a simple kinematic model for the velocity-dispersion profile of the Galactic bulge.
In the course of the Pico dos Dias survey (PDS), we identified the stellar-like object PDS 456 at coordinates α = 17h28m19.s796, δ = -14°15'5587 (epoch 2000), with a relatively nearby (z = 0.184) and bright (B = 14.69) quasar. Its position at Galactic coordinates l = 104, b = +112, near the bulge of the Galaxy, may explain why it was not detected before. The optical spectrum of PDS 456 is typical of a luminous quasar, showing a broad (FWHM ~ 4000 km s-1) Hβ line, very intense Fe II lines, and a weak [O III] λ5007 line. PDS 456 is associated to the infrared source IRAS 17254-1413 with a 60 μm infrared luminosity L60 = 3.8 × 1045 ergs s-1. The relatively flat slopes in the infrared [α(25, 60) = -0.33 and α(12, 25) = -0.78] and a flat power index in the optical (Fν ν-0.72) may indicate a low dust content. A good match between the position of PDS 456 and the position of the X-ray source RXS J172819.3-141600 implies an X-ray luminosity LX = 2.8 × 1044 ergs s-1. The good correlation between the strength of the emission lines in the optical and the X-ray luminosity, as well as the steep optical to X-ray index estimated (αOX = -1.64), suggests that PDS 456 is radio quiet. A radio survey previously performed in this region yields an upper limit for radio power at about 5 GHz of approximately 2.6 × 1030 ergs-1 Hz-1. We estimate the Galactic reddening in this line of sight to be AB 2.0, implying an absolute magnitude MB = -26.7 (using H0 = 75 km s-1 Mpc-1 and q0 = 0). In the optical, PDS 456 is therefore 1.3 times more luminous than 3C 273 and the most luminous quasar in the nearby (z ≤ 0.3) universe.
We derive improved versions of the relations between supermassive black hole mass (M BH) and host-galaxy bulge velocity dispersion (σ) and luminosity (L; the M-σ and M-L relations), based on 49 M BH measurements and 19 upper limits. Particular attention is paid to recovery of the intrinsic scatter (0) in both relations. We find log(M BH/M ☉) = α + βlog(σ/200 km s–1) with (α, β, 0) = (8.12 ± 0.08, 4.24 ± 0.41, 0.44 ± 0.06) for all galaxies and (α, β, 0) = (8.23 ± 0.08, 3.96 ± 0.42, 0.31 ± 0.06) for ellipticals. The results for ellipticals are consistent with previous studies, but the intrinsic scatter recovered for spirals is significantly larger. The scatter inferred reinforces the need for its consideration when calculating local black hole mass function based on the M-σ relation, and further implies that there may be substantial selection bias in studies of the evolution of the M-σ relation. We estimate the M-L relationship as log(M BH/M ☉) = α + βlog(LV /1011 L ☉,V ) of (α, β, 0) = (8.95 ± 0.11, 1.11 ± 0.18, 0.38 ± 0.09); using only early-type galaxies. These results appear to be insensitive to a wide range of assumptions about the measurement errors and the distribution of intrinsic scatter. We show that culling the sample according to the resolution of the black hole's sphere of influence biases the relations to larger mean masses, larger slopes, and incorrect intrinsic residuals.
We performed a blind search for narrow absorption features at energies greater than 6.4 keV in a sample of 42 radio-quiet AGNs observed with XMM-Newton. We detect 36 narrow absorption lines on a total of 101 XMM-Newton EPIC pn observations. The number of absorption lines at rest-frame energies E>7 keV is 22. Their global probability to be generated by random fluctuations is very low, less than 3x10^-8, and their detection have been independently confirmed by a spectral analysis of the MOS data, with associated random probability <10^-7. We identify the lines as Fe XXV and Fe XXVI K-shell resonant absorption. They are systematically blue-shifted, with a velocity distribution ranging from zero up to 0.3c, with a peak and mean value at 0.1c. We detect variability of the lines on both EWs and blue-shifted velocities among different observations even on time-scales as short as a few days, possibly suggesting somewhat compact absorbers. Moreover, we find no significant correlation between the cosmological red-shifts of the sources and the lines blue-shifted velocities, ruling out any systematic contamination by local absorption. If we define Ultra-fast Outflows (UFOs) those highly ionized absorbers with outflow velocities higher than 10^4 km/s, then the majority of the lines are consistent with being associated to UFOs and the fraction of objects with detected UFOs in the whole sample is at least 35%. This fraction is similar for Type 1 and Type 2 sources. The global covering fraction of the absorbers is consequently estimated to be in the range C=0.4-0.6, thereby implying large opening angles. These lines indicate that UFOs are a rather common phenomenon observable in the central regions of these sources and they are probably the direct signature of AGN accretion disk winds/ejecta. The detailed photo-ionization modeling of these absorbers is presented in a companion paper. Comment: 35 pages, accepted for publication in Astronomy & Astrophysics; corrected references
The solar chemical composition is an important ingredient in our understanding of the formation, structure and evolution of both the Sun and our solar system. Furthermore, it is an essential reference standard against which the elemental contents of other astronomical objects are compared. In this review we evaluate the current understanding of the solar photospheric composition. In particular, we present a re-determination of the abundances of nearly all available elements, using a realistic new 3-dimensional (3D), time-dependent hydrodynamical model of the solar atmosphere. We have carefully considered the atomic input data and selection of spectral lines, and accounted for departures from LTE whenever possible. The end result is a comprehensive and homogeneous compilation of the solar elemental abundances. Particularly noteworthy findings are significantly lower abundances of carbon, nitrogen, oxygen and neon compared with the widely-used values of a decade ago. The new solar chemical composition is supported by a high degree of internal consistency between available abundance indicators, and by agreement with values obtained in the solar neighborhood and from the most pristine meteorites. There is, however, a stark conflict with standard models of the solar interior according to helioseismology, a discrepancy that has yet to find a satisfactory resolution. Comment: Due to ARAA rules, the actual published version is not allowed to be placed on arxiv.org. We recommend the interested reader to download the article from ARAA at http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.astro.46.060407.145222 rather than using the arxiv.org version
We calculate the efficiency of iron K line emission and iron K absorption in photoionized models using a new set of atomic data. These data are more comprehensive than those previously applied to the modeling of iron K lines from photoionized gases, and allow us to systematically examine the behavior of the properties of line emission and absorption as a function of the ionization parameter, density and column density of model constant density clouds. We show that, for example, the net fluorescence yield for the highly charged ions is sensitive to the level population distribution produced by photoionization, and these yields are generally smaller than those predicted assuming the population is according to statistical weight. We demonstrate that the effects of the many strongly damped resonances below the K ionization thresholds conspire to smear the edge, thereby potentially affecting the astrophysical interpretation of absorption features in the 7-9 keV energy band. We show that the centroid of the ensemble of K(alpha) lines, the K(beta) energy, and the ratio of the K(alpha(sub 1)) to K(alpha(sub 2)) components are all diagnostics of the ionization parameter of our model slabs.
The parameterized extinction data of Fitzpatrick and Massa (1986, 1988) for the ultraviolet and various sources for the optical and near-infrared are used to derive a meaningful average extinction law over the 3.5 micron to 0.125 wavelength range which is applicable to both diffuse and dense regions of the interstellar medium. The law depends on only one parameter R(V) = A(V)/E(B-V). An analytic formula is given for the mean extinction law which can be used to calculate color excesses or to deredden observations. The validity of the law over a large wavelength interval suggests that the processes which modify the sizes and compositions of grains are stochastic in nature and very efficient.
Winds from accretion disks in cataclysmic variable stars are ubiquitous. Observations by IUE reveal P Cygni-shaped profiles of high-ionization lines which are attributed to these winds. We have studied the formation of UV emission lines in cataclysmic variables by constructing kinematical models of biconical rotating outflows from disks around white dwarfs. The photoionization in the wind is calculated taking into account the radiation fields of the disk, the boundary layer, and the white dwarf. The 3D radiative transfer is solved in the Sobolev approximation. Effects on the line shapes of varying basic physical parameters of the wind are shown explicitly. We identify and map the resonant scattering regions in the wind which have strongly biconical character regardless of the assumed velocity and radiation fields. Rotation at the base of the wind introduces a radial shear which decreases the line optical depth and reduces the line core intensity. We find that it is possible to reproduce the observed P Cygni line shapes and make some predictions to be verified in high-resolution observations.
Spectroscopic observations of quasar outflows at rest-frame 500–1000 Å have immense diagnostic power. We present analyses
of such data, where absorption troughs from O iv and O iv* allow us to obtain the distance of the outflows from the AGN and troughs from Ne viii and Mg x reveal the warm absorber phase of the outflow. Their inferred column densities, combined with those of O vi, N iv and H i, yield two important results. (1) The outflow shows two ionization phases, where the high-ionization phase carries the bulk
of the material. This is similar to the situation seen in X-ray warm absorber studies. Furthermore, the low-ionization phase
is inferred to have a volume filling factor of 10−5–10−6. (2) We determine a distance of 3000 pc from the outflow to the central source using the O iv*/O iv column density ratio and the knowledge of the ionization parameter. Since this is a typical high-ionization outflow, we can
determine robust values for the outflow's mass flux and kinetic luminosity of 40 M⊙ yr−1 and 1045 erg s−1, respectively, where the latter is roughly equal to 1 per cent of the bolometric luminosity. Such a large kinetic luminosity
and mass flow rate measured in a typical high-ionization wind suggest that quasar outflows are a major contributor to AGN
feedback mechanisms.
The formation of massive black holes may precede the epoch that
characterises the peak of galaxy formation, as characterized by the star
formation history in luminous galaxies. Hence protogalactic star
formation may be profoundly affected by quasar-like nuclei and their
associated extensive energetic outflows. We derive a relation between
the mass of the central supermassive black hole and that of the galaxy
spheroidal component, and comment on other implications for galaxy
formation scenarios.
We derive an MBH-σ relation between supermassive black hole mass and stellar velocity dispersion in galaxy bulges that results from self-regulated,
energy-conserving feedback. The relation is of the form MBHvw ∝ σ5, where vw is the velocity of the wind driven by the black hole. We take a sample of quiescent early-type galaxies and bulges with measured
black hole masses and velocity dispersions and use our model to infer the wind speeds they would have had during an active
phase. This approach, in effect, translates the scatter in the observed MBH-σ relation into a distribution of vw. There are some remarkable similarities between the distributions of black hole wind speeds that we obtain and the distributions
of outflow speeds observed in local active galactic nuclei, including a comparable median of vw = 0.035c.
How can we test if a supermassive black hole lies at the heart of every active galactic nucleus? What are LINERS, BL Lacs, N galaxies, broad-line radio galaxies and radio-quiet quasars and how do they compare? This timely textbook answers these questions in a clear, comprehensive and self-contained introduction to active galactic nuclei - for graduate students in astronomy and physics. The study of AGN is one of the most dynamic areas of contemporary astronomy, involving one fifth of all research astronomers. This textbook provides a systematic review of the observed properties of AGN across the entire electromagnetic spectrum, examines the underlying physics, and shows how the brightest AGN, quasars, can be used to probe the farthest reaches of the Universe. This book serves as both an entry point to the research literature and as a valuable reference for researchers in the field.
Recent X-ray observations of intense high-speed outflows in quasars suggest that supercritical accretion on to the central black hole may have an important effect on a host galaxy. I revisit some ideas of Silk and Rees, and assume such flows occur in the final stages of building up the black hole mass. It is now possible to model explicitly the interaction between the outflow and the host galaxy. This is found to resemble a momentum-driven stellar wind bubble, implying a relation MBH = (fg�/2�G2)�4 ≃ 1.5 × 108�4200 M⊙ between black hole mass and bulge velocity dispersion (fg = gas fraction of total matter density, � = electron scattering opacity), without free parameters. This is remarkably close to the observed relation in both slope and normalization. This result suggests that the central black holes in galaxies gain most of their mass in phases of super-Eddington accretion, which are presumably obscured or at high redshift. Observed super-Eddington quasars are apparently late in growing their black hole masses.
Using a Monte Carlo method, we derive approximations to Green's
functions for the Compton reflection of X-rays and gamma-rays by cold
electrons. In Compton reflection, X-rays and gamma-rays emitted by a
source impinge upon a slab (e.g., an accretion disc) and re-emerge with
a spectrum altered by Compton scattering and bound-free absorption. The
obtained Green's functions are dependent on the viewing angle of the
reflecting slab, which extends the previous treatments of the problem,
in which the reflected spectra were integrated over all viewing angles.
The dependence on the viewing angle is especially important in hard
X-rays and soft gamma-rays, in which regime the reflected spectrum
strongly hardens with increasing viewing angle. This is an important
effect for modelling gamma-ray spectra of active galactic nuclei and
Galactic black hole candidates, where the presence of Compton reflection
has been established before from X-ray data.
Recent work on the X-ray spectra of Seyfert galaxies has shown the
presence of a reflection component due to the hard X-ray continuum
scattering from, and causing fluorescence by, cold matter. The strength
of the reflection spectrum is usually consistent with the hard X-rays
being emitted above a flat accretion disk. In this paper we calculate
reflection spectra for cases where the hard X-rays photoionize the
surface layers of the disk to the extent that the main X-ray absorbers
are significantly ionized. The temperature, ionization state and
spectrum are computed in a fully self-consistent manner for the inner,
radiation pressure dominated part of an accretion disk. The reflection
spectra are steeper, when the accretion rate exceeds 10 percent of the
Eddington value, than the incident continuum in the soft X-ray band;
they are also rich in emission lines, which may prove to be good
diagnostics of the conditions of the inner regions around accreting
black holes.
We present the results of a new spectroscopic study of Fe K-band absorption
in Active Galactic Nuclei (AGN). Using data obtained from the Suzaku public
archive we have performed a statistically driven blind search for Fe XXV Hea
and/or Fe XXVI Lyb absorption lines in a large sample of 51 type 1.0-1.9 AGN.
Through extensive Monte Carlo simulations we find statistically significant
absorption is detected at E>6.7 keV in 20/51 sources at the P(MC)>95% level,
which corresponds to ~40% of the total sample. In all cases, individual
absorption lines are detected independently and simultaneously amongst the two
(or three) available XIS detectors which confirms the robustness of the line
detections. The most frequently observed outflow phenomenology consists of two
discrete absorption troughs corresponding to Fe XXV Hea and Fe XXVI Lyb at a
common velocity shift. From xstar fitting the mean column density and
ionisation parameter for the Fe K absorption components are log(NH/cm^{-2})~23
and log(xi/erg cm s^{-1})~4.5, respectively. Measured outflow velocities span a
continuous range from <1,500 km/s up to ~100,000 km/s, with mean and median
values of ~0.1c and ~0.056c, respectively. The results of this work are
consistent with those recently obtained using XMM-Newton and independently
provides strong evidence for the existence of very highly-ionised circumnuclear
material in a significant fraction of both radio-quiet and radio-loud AGN in
the local universe.
We report on the highest to date signal-to-noise ratio X-ray spectrum of the luminous quasar PDS 456, as obtained during two XMM-Newton orbits in 2007 September. The present spectrum is considerably different from several previous X-ray spectra recorded for PDS 456 since 1998. The ultra-high-velocity outflow seen as recently as 2007 February is not detected in absorption. Conversely, a significant reflection component is detected (Δχ2 = 313 compared to a simple absorbed power law). The reflection model suggests that the reflecting medium may be outflowing at a velocity v/c = –0.06 ± 0.02 (Δχ2 = 28 compared to v/c = 0). The present spectrum is analyzed in the context of the previous ones in an attempt to understand all spectra within the framework of a single model. We examine whether an outflow with variable partial covering of the X-ray source along the line of sight that also reflects the source from other lines of sight can explain the dramatic variations in the broadband spectral curvature of PDS 456. It is established that absorption plays a major role in shaping the spectrum of other epochs, while the 2007 XMM-Newton spectrum is dominated by reflection, and the coverage of the source by the putative outflow is small (<20%).
We present results of calculations using the XSTAR version 2 computer code. This code is loosely based on the XSTAR version 1 code, which has been available for public use for some time. However, it represents an improvement and update in several major respects, including atomic data, code structure, user interface, and improved physical description of ionization/excitation. In particular, it now is applicable to high-density situations in which significant excited atomic level populations are likely to occur. We describe the computational techniques and assumptions and present sample runs with particular emphasis on high-density situations.
ABSTRACTA common model invoked to describe the X-ray spectra of active galaxies includes a relativistically blurred reflection component, which in some cases can be the dominant contributor to the received flux. Alternative interpretations are often based around complex absorption, and to date it has proven difficult to determine between these two viable models. Recent works on Suzaku observations of the active nuclei in NGC 1365, 1H 0419–577 and PDS 456 have found the presence of strong X-ray emission at high (∼10–50 keV) energies, referred to as ‘hard excesses’, and it has been claimed that this emission cannot be explained with simple disc reflection models. Here we investigate the high-energy emission in these sources by constructing disc reflection models and show that they can successfully reproduce the observed spectra. In addition, we find the behaviour of NGC 1365, 1H 0419–577 in these observations to be broadly consistent with previous work on disc reflection interpretations.
High-velocity outflows from active galactic nuclei are a well-known phenomenon in terms of the broad absorption lines seen
in the ultraviolet/optical. More recently, similar, possibly related, outflows have been reported in the X-ray. The most extreme
example is seen in the nearby, luminous QSO PDS 456, which displays a massive, high-velocity (50 000 km s−1), high-ionization X-ray outflow of 10 Mࣻ yr−1. Here we present the ultraviolet spectrum of PDS 456 as observed by the Hubble Space Telescope. We find that the ultraviolet spectrum is also extreme, displaying very broad emission lines, with C iv λ1549 blueshifted by 5000 km s−1 and a broad Lyα absorption trough blueshifted by 14 000–24 000 km s−1. No strong, broad high-ionization absorption features are seen. We interpret the combined ultraviolet and X-ray spectrum
of PDS 456 as the signature of a decelerating, cooling outflow, which may be driven by radiation and/or magnetic field. This
outflow may be the source of some of the broad emission- and absorption-line gas.
Narrow line Seyfert 1 galaxies are generally accreting at high fractions of the Eddington limit. They can show complex X-ray
spectra, with a strong ‘soft excess’ below 2 keV and a sharp drop at ∼7 keV. There is strong evidence linking the soft excess
to either reflection or absorption from relativistic, partially ionized material close to the black hole. The reflection models
can also simultaneously produce the 7-keV feature from fluorescent iron Kα line emission from the disc. Here we show that
absorption can also produce a sharp feature at 7 keV from the P Cygni profile which results from absorption/scattering/emission
of He- and H-like iron Kα resonance lines in the wind. We demonstrate this explicitly by fitting the iron feature seen in
XMM–Newton data from 1H 0707-495 to a P Cygni profile. The resulting column and ionization required to produce this feature are probably
larger than those needed to produce the soft excess. Nonetheless, the absorbing material could still be a single structure
with stratified ionization such as that produced by the ionization instability.
We present the results of a uniform analysis of the soft X-ray spectra of 15 type I active galactic nuclei (AGN) observed with the high-resolution X-ray gratings onboard Chandra. We found that 10 out of the 15 AGN exhibit signatures of an intrinsic ionized absorber. The absorbers are photoionized and outflowing, with velocities in the range ∼101− 103 km s−1. The column density of the warm absorbing gas is ∼1020−23 cm−2. Nine out of the 10 AGN exhibiting warm absorption are best fitted by multiple ionization components and three out of the 10 AGN require multiple kinematic components. The warm absorbing gas in our AGN sample has a wide range of ionization parameter, spanning roughly four orders of magnitude (ξ∼ 100−4 erg cm s−1) in total, and often spanning three orders of magnitude in the same gas. Warm absorber components with ionization parameter ξ < 10 generate an unresolved transition array due to Fe in seven out of the 10 AGN exhibiting warm absorption. These low ionization state absorbers may also carry away the largest mass outflows from the AGN. The mass outflow rate depends critically on the volume filling factor of the gas, which cannot yet be directly measured. However, upper limits on the mass outflow rates for filling factors of unity can be much greater than the expected accretion rate on to the central supermassive black hole and filling factors as small as 1 per cent can give outflow rates comparable to the accretion rate. There appears to be a gap in the outflow velocities in our sample between ∼300 and 500 km s−1, the origin of which is not clear. The outflow components with velocities below this gap tend to be associated with lower column densities than those with velocities above the gap.
We show that black holes accreting at or above the Eddington rate probably produce winds that are optically thick in the continuum, whether in quasars or in X-ray binaries. The photospheric radius and outflow speed are proportional to and respectively, where is the mass outflow rate. The momentum outflow rate is always of the order of LEdd/c. Blackbody emission from these winds may provide the big blue bump in some quasars and active galactic nuclei, as well as ultrasoft X-ray components in ultraluminous X-ray sources.
Using the results of a previous X-ray photo-ionization modelling of
blue-shifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs
observed with XMM-Newton, in this letter we estimate the location and
energetics of the associated ultra-fast outflows (UFOs). Due to significant
uncertainties, we are essentially able to place only lower/upper limits. On
average, their location is in the interval ~0.0003-0.03pc (~10^2-10^4 r_s) from
the central black hole, consistent with what is expected for accretion disk
winds/outflows. The mass outflow rates are constrained between ~0.01-1
M_{\odot} yr^{-1}, corresponding to >5-10% of the accretion rates. The average
lower-upper limits on the mechanical power are log\dot{E}_K~42.6-44.6 erg
s^{-1}. However, the minimum possible value of the ratio between the mechanical
power and bolometric luminosity is constrained to be comparable or higher than
the minimum required by simulations of feedback induced by winds/outflows.
Therefore, this work demonstrates that UFOs are indeed capable to provide a
significant contribution to the AGN cosmological feedback, in agreement with
theoretical expectations and the recent observation of interactions between AGN
outflows and the interstellar medium in several Seyferts galaxies.
It is widely suspected that active galactic nucleus (AGN) activity ultimately sweeps galaxies clear of their gas. We work out the observable properties required to achieve this. Large-scale AGN-driven outflows should have kinetic luminosities ~η L
Edd/2 ~ 0.05 L
Edd and momentum rates ~20 L
Edd/c, where L
Edd is the Eddington luminosity of the central black hole and η ~ 0.1 its radiative accretion efficiency. This creates an expanding two-phase medium in which molecular species coexist with hot gas, which can persist after the central AGN has switched off. This picture predicts outflow velocities ~1000-1500 km s–1 and mass outflow rates up to 4000 M
☉ yr–1 on kpc scales, fixed mainly by the host galaxy velocity dispersion (or equivalently black hole mass). All these features agree with those of outflows observed in galaxies such as Mrk231. This strongly suggests that AGN activity is what sweeps galaxies clear of their gas on a dynamical timescale and makes them red and dead. We suggest future observational tests of this picture.
We use a large sample of upper limits and accurate estimates of supermassive black hole (SMBH) masses coupled with libraries
of host galaxy velocity dispersions, rotational velocities and photometric parameters extracted from Sloan Digital Sky Survey i-band images to establish correlations between the SMBH and host galaxy parameters. We test whether the mass of the black
hole, M•, is fundamentally driven by either local or global galaxy properties. We explore correlations between M• and stellar velocity dispersion σe, i-band bulge luminosity Li, bulge, bulge mass Mbulge, bulge Sérsic index n, bulge mean effective surface brightness 〈μe, bulge〉, i-band luminosity of the galaxy Li, gal, galaxy stellar mass , maximum circular velocity Vc, and galaxy dynamical and effective masses Mdyn, gal and Me, gal. We verify the tightness of the M•–σe relation and find that correlations with other galaxy parameters do not yield tighter trends. We do not find differences
in the M•–σe relation of barred and unbarred galaxies. The M•–σe relation of pseudo-bulges is also coarser and has a different slope than that involving classical bulges. The M•–Mbulge is not as tight as the M•–σe relation, despite the bulge mass proving to be a better proxy of M• than bulge luminosity, and despite adding the bulge effective radius as an additional fitting parameter. Contrary to various
published reports, we find a rather poor correlation between M• and n (or 〈μe, bulge〉), suggesting that M• is not related to the bulge light concentration. The correlations between M• and galaxy luminosity or mass are not a marked improvement over the M•–σe relation. These scaling relations depend sensitively on the host galaxy morphology: early-type galaxies follow a tighter
relation than late-type galaxies. If Vc is a proxy for the dark matter halo mass, the large scatter of the M•–Vc relation then suggests that M• is more coupled to the baryonic rather than the dark matter. We have tested the need for a third parameter in the M• scaling relations, through various linear correlations with bulge and galaxy parameters, only to confirm that the Fundamental
Plane of the SMBH is mainly driven by σe with a small tilt due to the effective radius. We provide a compendium of galaxy structural properties for most of the SMBH
hosts known to date.
Narrow absorption lines seen in the 2–10 keV spectra of active galaxies and Galactic black holes are normally attributed to
iron in high‐velocity outflows or inflows. We consider the possibility that such features could arise naturally in the accretion
disc. Resonant absorption by highly ionized iron (e.g. Fe xxvi and Fe xxv) in an optically thin plasma that is located above the disc and rotating with it could reproduce narrow features in the reflection
component of the spectrum as it emerges from the disc. Depending on the inclination of the disc and the exact geometry of
the hot plasma (e.g. whether it blanket the disc or a ring), apparently narrow absorption features could be detected between
4 and 10 keV. Such an explanation requires no high‐velocity outflow/inflow and is consistent with a reflection‐based interpretation
for accreting black holes systems.
We present a mid-IR investigation of the scaling relations between
supermassive black hole masses (MBH) and the structural parameters of the host
spheroids in local galaxies. The work is based on two-dimensional bulge-disk
decompositions of Spitzer/IRAC 3.6 um images of 57 galaxies with MBH estimates.
Our estimates of effective radii (Re) and surface brightnesses, combined with
velocity dispersions (sigma) from the literature, define a FP relation
consistent with previous determinations but doubling the observed range in Re.
None of our galaxies is an outlier of the FP, demonstrating the accuracy of our
bulge-disk decomposition which also allows us to independently identify
pseudobulges in our sample. We calibrate M/L at 3.6 um by using the tight
Mdyn-Lbul relation (~0.1 dex of rms) and find that no color corrections are
required to estimate the stellar mass. The 3.6 um luminosity is thus the best
tracer of Mstar yet studied. We then explore the connection between MBH and
bulge structural parameters (luminosity, mass, effective radius). We find tight
correlations of MBH with both 3.6 um bulge luminosity and dynamical mass
(MBH/Mdyn~1/1000), with rms of ~0.35 dex, similar to the MBH-sigma relation.
Our results are consistent with previous determinations at shorter wavelengths.
By using our calibrated M/L, we rescale MBH-Lbul to obtain the MBH-Mstar
relation, which can be used as the local reference for high-z studies which
probe the cosmic evolution of MBH-galaxy relations and where the stellar mass
is inferred directly from luminosity measurements. The analysis of pseudobulges
shows that 4 out of 9 lie on the scaling relations within the observed scatter,
while those with small MBH are significantly displaced. We explore the
different origins for such behavior, while considering the possibility of
nuclear morphological components not reproduced by our two-dimensional
decomposition.
We show that the black hole-bulge mass scaling relations observed from the
local to the high-z Universe can be largely or even entirely explained by a
non-causal origin, i.e. they do not imply the need for any physically coupled
growth of black hole and bulge mass, for example through feedback by active
galactic nuclei (AGN). Provided some physics for the absolute normalisation,
the creation of the scaling relations can be fully explained by the
hierarchical assembly of black hole and stellar mass through galaxy merging,
from an initially uncorrelated distribution of BH and stellar masses in the
early Universe. We show this with a suite of dark matter halo merger trees for
which we make assumptions about (uncorrelated) black hole and stellar mass
values at early cosmic times. We then follow the halos in the presence of
global star formation and black hole accretion recipes that (i) work without
any coupling of the two properties per individual galaxy and (ii) correctly
reproduce the observed star formation and black hole accretion rate density in
the Universe. With disk-to-bulge conversion in mergers included, our
simulations even create the observed slope of ~1.1 for the
M_BH-M_bulge-relations at z=0. This also implies that AGN feedback is not a
required (though still a possible) ingredient in galaxy evolution. In light of
this, other mechanisms that can be invoked to truncate star formation in
massive galaxies are equally justified.
I show that Eddington accretion episodes in AGN are likely to produce winds with velocities $v \sim 0.1c$ and ionization parameters up to $\xi \sim 10^4$ (cgs), implying the presence of resonance lines of helium-- and hydrogenlike iron. These properties are direct consequences of momentum and mass conservation respectively, and agree with recent X-ray observations of fast outflows from AGN. Because the wind is significantly subluminal, it can persist long after the AGN is observed to have become sub--Eddington. The wind creates a strong cooling shock as it interacts with the interstellar medium of the host galaxy, and this cooling region may be observable in an inverse Compton continuum and lower--excitation emission lines associated with lower velocities. The shell of matter swept up by the (`momentum--driven') shocked wind must propagate beyond the black hole's sphere of influence on a timescale $\la 3\times 10^5$ yr. Outside this radius the shell stalls unless the black hole mass has reached the value $M_{\sigma}$ implied by the $M - \sigma$ relation. If the wind shock did not cool, as suggested here, the resulting (`energy--driven') outflow would imply a far smaller SMBH mass than actually observed. In galaxies with large bulges the black hole may grow somewhat beyond this value, suggesting that the observed $M -\sigma$ relation may curve upwards at large $M$. Minor accretion events with small gas fractions can produce galaxy--wide outflows with velocities significantly exceeding $\sigma$, including fossil outflows in galaxies where there is little current AGN activity. Some rare cases may reveal the energy--driven outflows which sweep gas out of the galaxy and establish the black hole--bulge mass relation. However these require the quasar to be at the Eddington luminosity. Comment: MNRAS, to appear
PDS 456 is a nearby (z=0.184), luminous (L_bol ~10^47 erg/s) type I quasar. A deep 190 ks Suzaku observation in February 2007 revealed the complex, broad band X-ray spectrum of PDS 456. The Suzaku spectrum exhibits highly statistically significant absorption features near 9 keV in the quasar rest--frame. We show that the most plausible origin of the absorption is from blue-shifted resonance (1s-2p) transitions of hydrogen-like iron (at 6.97 keV in the rest frame). This indicates that a highly ionized outflow may be present moving at near relativistic velocities (~0.25c). A possible hard X-ray excess is detected above 15 keV with HXD (at 99.8% confidence), which may arise from high column density gas (Nh>10^24cm^-2) partially covering the X-ray emission, or through strong Compton reflection. Here we propose that the iron K-shell absorption in PDS 456 is associated with a thick, possibly clumpy outflow, covering about 20% of $4\pi$ steradian solid angle. The outflow is likely launched from the inner accretion disk, within 15-100 gravitational radii of the black hole. The kinetic power of the outflow may be similar to the bolometric luminosity of PDS 456. Such a powerful wind could have a significant effect on the co-evolution of the host galaxy and its supermassive black hole, through feedback. Comment: 45 pages, 11 figures, 4 tables, accepted for publication in ApJ
We propose a two-stage model for the effects of feedback from a bright quasar on the cold gas in a galaxy. It is difficult for feedback from near the accretion disk to directly impact dense molecular clouds at ~kpc. But if such feedback can drive a weak wind or outflow in the hot, diffuse ISM (a relatively 'easy' task), then in the wake of such an outflow passing over a cold cloud, a combination of instabilities will drive the cloud material to effectively expand in the direction perpendicular to the outflow. Such expansion dramatically increases the effective cross section of the cloud material and makes it more susceptible to ionization and momentum coupling from absorption of the incident quasar radiation field. Even a moderate effect of this nature can dramatically alter the ability of clouds at large radii to be fully ionized and driven into a secondary outflow by radiation pressure. Since the amount of momentum and volume which can be ionized by observed quasar radiation field is more than sufficient to affect the entire cold gas supply once it has been altered in this manner (and the 'initial' feedback need only initiate a moderate wind in the low-density hot gas), this reduces by an order of magnitude the required energy budget for feedback to affect a host galaxy. Instead of ~5% of the radiated energy (~100% momentum) needed if the initial feedback must directly heat or blow out the galactic gas, if only ~0.5% of the luminosity (~10% momentum) can couple to drive the initial hot outflow, this mechanism could be efficient. This amounts to hot gas outflow rates from near the accretion disk of only 5-10% of the BH accretion rate. Comment: 9 pages, 2 figures, accepted to MNRAS (revised to match published version, methodology expanded)
We report two new XMM-Newton observations of PG1211+143 in December 2007,
again finding evidence of the fast outflow of highly ionised gas first detected
in 2001. Stacking the new spectra with those from two earlier XMM-Newton
observations reveals strong and broad emission lines of FeXXV and OVIII,
indicating the fast outflow to be persistent and to have a large covering
factor. This finding confirms a high mass rate for the ionised ouflow in
PG1211+143 and provides the first direct measurement of a wide angle,
sub-relativistic outflow from an AGN transporting mechanical energy with the
potential to disrupt the growth of the host galaxy. We suggest PG1211+143 may
be typical of an AGN in a rapid super-Eddington growth phase.
In the early Universe, while galaxies were still forming, black holes as massive as a billion solar masses powered quasars. Supermassive black holes are found at the centres of most galaxies today, where their masses are related to the velocity dispersions of stars in their host galaxies and hence to the mass of the central bulge of the galaxy. This suggests a link between the growth of the black holes and their host galaxies, which has indeed been assumed for a number of years. But the origin of the observed relation between black hole mass and stellar velocity dispersion, and its connection with the evolution of galaxies, have remained unclear. Here we report simulations that simultaneously follow star formation and the growth of black holes during galaxy-galaxy collisions. We find that, in addition to generating a burst of star formation, a merger leads to strong inflows that feed gas to the supermassive black hole and thereby power the quasar. The energy released by the quasar expels enough gas to quench both star formation and further black hole growth. This determines the lifetime of the quasar phase (approaching 100 million years) and explains the relationship between the black hole mass and the stellar velocity dispersion.
The warm electron scattering region posited in 1985 by Antonucci and Miller to exist in NGC 1068 may be a characteristic feature of Seyfert galaxies. Whenever it exists, it presents a unique signature in Fe X-ray features. Predictions of the strength of the Fe K-edge and K-alpha line in both type 1 and type 2 Seyfert galaxies are presented and interpreted.