P. Leto

Boston University, Boston, Massachusetts, United States

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Publications (89)316.76 Total impact

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    ABSTRACT: Mrk 501 is one of the brightest blazars at TeV energies and has been extensively studied since its first VHE detection in 1996. Our goal is to characterize in detail the source gamma-ray emission, together with the radio-to-X-ray emission, during the non-flaring (low) activity, which is less often studied than the occasional flaring (high) activity. We organized a multiwavelength (MW) campaign on Mrk 501 between March and May 2008. This multi-instrument effort included the most sensitive VHE gamma-ray instruments in the northern hemisphere, namely the imaging atmospheric Cherenkov telescopes MAGIC and VERITAS, as well as Swift, RXTE, the F-GAMMA, GASP-WEBT, and other collaborations and instruments. Mrk 501 was found to be in a low state of activity during the campaign, with a VHE flux in the range of 10%-20% of the Crab nebula flux. Nevertheless, significant flux variations were detected with various instruments, with a trend of increasing variability with energy. The broadband spectral energy distribution during the two different emission states of the campaign can be adequately described within the homogeneous one-zone synchrotron self-Compton model, with the (slightly) higher state described by an increase in the electron number density. This agrees with previous studies of the broadband emission of this source during flaring and non-flaring states. We report for the first time a tentative X-ray-to-VHE correlation during a low VHE activity. Although marginally significant, this positive correlation between X-ray and VHE, which has been reported many times during flaring activity, suggests that the mechanisms that dominate the X-ray/VHE emission during non-flaring-activity are not substantially different from those that are responsible for the emission during flaring activity.
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    ABSTRACT: We present radio observations of two supernova remnants and four planetary nebulae with the Very Large Array and the Green Bank Telescope. These objects are part of a larger sample of radio sources, discussed in a previous paper, counterpart of the MIPSGAL 24-micron compact bubbles. For the two supernova remnants we combined the interferometric observations with single-dish data to obtain both a high resolution and a good sensitivity to extended structures. We discuss in detail the entire combination procedure adopted and the reliability of the resulting maps. For one supernova remnant we pose a more stringent upper limit for the flux density of its undetected pulsar, and we also show prominent spectral index spatial variations, probably due to inhomogeneities in the magnetic field and in its ejecta or to an interaction between the supernova shock and molecular clouds. We eventually use the 5-GHz maps of the four planetary nebulae to estimate their distance and their ionized mass.
    Monthly Notices of the Royal Astronomical Society 10/2014; 445(4). DOI:10.1093/mnras/stu2081 · 5.23 Impact Factor
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    ABSTRACT: Late stages of stellar evolution are characterized by copious mass-loss events whose signature is the formation of circumstellar envelopes (CSE). Planck multi frequency measurements have provided relevant information on a sample of Galactic planetary nebulae (PNe) in this important and relatively unexplored observational band between 30 and 857GHz. Planck enables the assembly of comprehensive PNe spectral energy distributions (SEDs) from radio through to far-infrared frequencies. Modelling of the derived SEDs provides us with information on physical properties of CSEs and the mass content of both main components: ionized gas, traced by the free-free emission at cm mm waves; and thermal dust, traced by the millimetre and far IR emission. In particular, the amount of ionized gas and dust has been derived here. Such quantities have also been estimated for the very young PN CRL618, where the strong variability observed in its radio and millimetre emission has previously prevented the construction of its SED. A morphological study of the Helix Nebula has also been performed. Planck maps reveal, for the first time, the spatial distribution of the dust inside the envelope, allowing us to identify different components, the most interesting of which is a very extended component (up to 1 pc) that may be related to a region where the slow expanding envelope is interacting with the surrounding interstellar medium. Moreover, in this object, thermal dust and H2 emission appear to be spatially correlated, providing hints of H2 formation on dust grain surfaces.
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    ABSTRACT: We present a multiwavelength analysis of the nebula around the candidate luminous blue variable G79.29+0.46. The study is based on our radio observations performed at the Expanded Very Large Array and at the Green Bank Telescope and on archival infrared datasets, including recent images obtained by the Herschel Space Observatory. We confirm that the radio central object is characterized by a stellar wind and derive a current mass-loss rate of about 1.4x10-6 Msun yr-1. We find the presence of a dusty compact envelope close to the star, with a temperature between 40 and 1200 K. We estimate for the outer ejecta an ionised gas mass of 1.51 Msun and a warm (60--85 K) dust mass of 0.02 Msun. Diagnostics of the far-infrared spectra indicate the presence of a photo-dissociation region around the ionised gas. Finally, we model the nebula with the photo-ionization code CLOUDY, using as input parameters those estimated from our analysis. We find for the central star a luminosity of 10^5.4 Lsun and an effective temperature of 20.4 kK.
    Monthly Notices of the Royal Astronomical Society 02/2014; DOI:10.1093/mnras/stu296 · 5.23 Impact Factor
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    ABSTRACT: MWC 930 is a star just ~2{\deg} above the Galactic plane whose nature is not clear and that has not been studied in detail so far. While a post-Asymptotic Giant Branch (AGB) classification was proposed in the past, studies of its optical spectrum and photometry pointed toward strong variability, therefore the object was reclassified as a Luminous Blue Variable (LBV) candidate. LBVs typically undergo phases of strong mass loss in the form of eruptions that can create shells of ejecta around the star. Our goal is to search for the presence of such a circumstellar nebula in MWC 930 and investigate its properties. To do so, we make use of space-based infrared data from our Spitzer campaign performed with the InfraRed Array Camera (IRAC) and the InfraRed Spectrograph (IRS) as well as data from optical and infrared (IR) surveys. In our Spitzer images, we clearly detect an extended shell around MWC 930 at wavelengths longer than 5 um. The mid-infrared spectrum is dominated by the central star and mostly shows forbidden lines of [FeII], with an underlying continuum that decreases with wavelength up to ~15 um and then inverts its slope, displaying a second peak around 60 um, evidence for cold dust grains formed in a past eruption. By modeling the SED, we identify two central components, besides the star and the outer shell. These extra sources of radiation are interpreted as material close to the central star, maybe due to a recent ejection. Features of C-bearing molecules or grains are not detected.
    Astronomy and Astrophysics 12/2013; 562. DOI:10.1051/0004-6361/201323099 · 4.48 Impact Factor
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    ABSTRACT: We report the radio observations of a sub-sample of the 428 galactic compact bubbles discovered at 24 $\mu$m with the MIPSGAL survey. Pervasive through the entire Galactic plane, these objects are thought to be different kinds of evolved stars. The very large majority of the bubbles (~ 70%) are however not yet classified. We conducted radio observations with the EVLA at 6 cm and 20 cm in order to obtain the spectral index of 55 bubbles. We found that at least 70 per cent of the 31 bubbles for which we were effectively able to compute the spectral index (or its lower limit) are likely to be thermal emitters. We were also able to resolve some bubbles, obtaining that the size of the radio nebula is usually similar to the IR size, although our low resolution (with respect to IR images) did not allow further morphological studies. Comparisons between radio flux densities and IR archive data from Spitzer and IRAS suggest that at least 3 unclassified bubbles can be treated as planetary nebula candidates.
    Monthly Notices of the Royal Astronomical Society 11/2013; 437(4). DOI:10.1093/mnras/stt2157 · 5.23 Impact Factor
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    ABSTRACT: New data from the Herschel Infrared Galactic Plane Survey (Hi-GAL) and the Expanded Very Large Array, together with ancillary multifrequency data from different archives, have provided a comprehensive picture of the circumstellar envelope (CSE) surrounding the Galactic luminous blue variable (LBV) candidate Gal 026.47+0.02. The high angular resolution of both the 70-μm and 6-cm maps has allowed us to appreciate finest details of the nebula, whose morphology is consistent with a series of nested tori. The inner torus, which is close to the central object, is fully ionized, indicating events of aspherical mass loss. We have derived the physical properties of the CSE, including, in particular, one of the highest current-day mass losses from the central object and a very massive nebula, which consists of, at least, 17 M⊙ of ionized gas, with 1.2–3.2 × 10−2 M⊙ in the form of dust. Altogether, the physical properties of Gal 026.47+0.02, including a very high stellar luminosity, point towards a very massive progenitor on the main sequence. According to the current models for Type IIn supernovae, the CSEs associated with possible progenitors have well constrained properties in both content and morphology. The derived physical characteristics of the nebula associated with Gal 026.47+0.02 actually satisfy all such requirements, providing some observational evidence of a direct link between a LBV and a possible Type IIn supernova.
    Monthly Notices of the Royal Astronomical Society 12/2012; 427(4):2975-2984. DOI:10.1111/j.1365-2966.2012.22018.x · 4.90 Impact Factor
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    ABSTRACT: The nebulae associated to four Luminous Blue Variables (LBVs) in the Large Magellanic Cloud (LMC) have been observed at 5.5 and 9 GHz using the Australia Telescope Compact Array, and radio emission has been detected for first time in these sources, R127, R143, S61 and S119. The radio maps of the nebulae have an angular resolution of \sim 1.5" and a sensitivity of 1.5-3.0\times10-2 mJy beam-1, and show a very similar morphology to that observed in H{\alpha}. This similarity permit us to assume that the H{\alpha} emission is not affected by strong intrinsic extinction due to dust within the nebulae. We estimate the masses of the ionized gas in the LBVs nebulae and their values are consistent with those measured in Galactic LBVs.
    Monthly Notices of the Royal Astronomical Society 07/2012; 426(1):181-186. DOI:10.1111/j.1365-2966.2012.21791.x · 5.52 Impact Factor
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    ABSTRACT: The quasar-type blazar 4C 38.41 (B3 1633+382) experienced a large outburst in 2011, which was detected throughout the entire electromagnetic spectrum. We present the results of low-energy multifrequency monitoring by the GASP project of the WEBT consortium and collaborators, as well as those of spectropolarimetric/spectrophotometric monitoring at the Steward Observatory. We also analyse high-energy observations of the Swift and Fermi satellites. In the optical-UV band, several results indicate that there is a contribution from a QSO-like emission component, in addition to both variable and polarised jet emission. The unpolarised emission component is likely thermal radiation from the accretion disc that dilutes the jet polarisation. We estimate its brightness to be R(QSO) ~ 17.85 - 18 and derive the intrinsic jet polarisation degree. We find no clear correlation between the optical and radio light curves, while the correlation between the optical and \gamma-ray flux apparently fades in time, likely because of an increasing optical to \gamma-ray flux ratio. As suggested for other blazars, the long-term variability of 4C 38.41 can be interpreted in terms of an inhomogeneous bent jet, where different emitting regions can change their alignment with respect to the line of sight, leading to variations in the Doppler factor \delta. Under the hypothesis that in the period 2008-2011 all the \gamma-ray and optical variability on a one-week timescale were due to changes in \delta, this would range between ~ 7 and ~ 21. If the variability were caused by changes in the viewing angle \theta\ only, then \theta\ would go from ~ 2.6 degr to ~ 5 degr. Variations in the viewing angle would also account for the dependence of the polarisation degree on the source brightness in the framework of a shock-in-jet model.
    Astronomy and Astrophysics 07/2012; 545. DOI:10.1051/0004-6361/201219492 · 4.48 Impact Factor
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    ABSTRACT: The blazar AO 0235+164 (z = 0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to {\gamma} -ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP- WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the {\gamma} -ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 Rg . We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus.
    The Astrophysical Journal 07/2012; 751(2). DOI:10.1088/0004-637X/751/2/159 · 6.28 Impact Factor
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    ABSTRACT: Optical observations at the Mount Maidanak Observatory in the framework of the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) reveal a rapid optical brightening of BL Lacertae. This is one of the 28 blazars for which the GASP performs a long-term, multiwavelength monitoring. The source brightness has recently increased from R = 13.66 +/- 0.01 on July 19.82 to R = 12.60 +/- 0.01 on July 22.97.
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    ABSTRACT: The nebulae associated to four Luminous Blue Variables (LBVs) in the Large Magellanic Cloud (LMC) have been observed at 5.5 and 9 GHz using the Australia Telescope Compact Array, and radio emission has been detected for first time in these sources, R127, R143, S61 and S119. The radio maps of the nebulae have an angular resolution of \sim 1.5" and a sensitivity of 1.5-3.0\times10-2 mJy beam-1, and show a very similar morphology to that observed in H{\alpha}. This similarity permit us to assume that the H{\alpha} emission is not affected by strong intrinsic extinction due to dust within the nebulae. We estimate the masses of the ionized gas in the LBVs nebulae and their values are consistent with those measured in Galactic LBVs.
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    ABSTRACT: We present time-resolved broad-band observations of the quasar 3C 279 obtained from multi-wavelength campaigns conducted during the first two years of the Fermi Gamma-ray Space Telescope mission. While investigating the previously reported gamma-ray/optical flare accompanied by a change in optical polarization, we found that the optical emission appears delayed with respect to the gamma-ray emission by about 10 days. X-ray observations reveal a pair of `isolated' flares separated by ~90 days, with only weak gamma-ray/optical counterparts. The spectral structure measured by Spitzer reveals a synchrotron component peaking in the mid-infrared band with a sharp break at the far-infrared band during the gamma-ray flare, while the peak appears in the mm/sub-mm band in the low state. Selected spectral energy distributions are fitted with leptonic models including Comptonization of external radiation produced in a dusty torus or the broad-line region. Adopting the interpretation of the polarization swing involving propagation of the emitting region along a curved trajectory, we can explain the evolution of the broad-band spectra during the gamma-ray flaring event by a shift of its location from ~ 1 pc to ~ 4 pc from the central black hole. On the other hand, if the gamma-ray flare is generated instead at sub-pc distance from the central black hole, the far-infrared break can be explained by synchrotron self-absorption. We also model the low spectral state, dominated by the mm/sub-mm peaking synchrotron component, and suggest that the corresponding inverse-Compton component explains the steady X-ray emission.
    The Astrophysical Journal 06/2012; 754(2). DOI:10.1088/0004-637X/754/2/114 · 6.28 Impact Factor
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    ABSTRACT: In this paper, we present new and archive radio measurements obtained with the Very Large Array of the magnetic chemically peculiar (MCP) star ? Orionis E. The radio data have been obtained at different frequencies and they are well distributed along the rotational phases. We analyse in detail the radio emission from ? Ori E with the aim of finding evidence for circularly polarized radio pulses. Up to now, among MCP stars, only CU Virginis has shown 100 per cent polarized time-stable radio pulses, explained as highly directive electron cyclotron maser emission, visible from Earth at particular rotational phases, like a pulsar. Our analysis shows that there is no hint of coherent emission at frequencies below 15 GHz. We conclude that the presence of a quadrupolar component of the magnetic field, dominant within few stellar radii from the star, where the maser emission should be generated, inhibits the onset of the cyclotron maser instability in ? Ori E.
    Monthly Notices of the Royal Astronomical Society 06/2012; 423(2):1766-1774. DOI:10.1111/j.1365-2966.2012.20997.x · 5.23 Impact Factor
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    ABSTRACT: In this paper we present new and archive radio measurements obtained with the Very Large Array of the magnetic chemically peculiar (MCP) star \sigma Ori E. The radio data have been obtained at different frequencies and are well distributed along the rotational phases. We analyze in detail the radio emission from \sigma Ori E with the aim to search evidence of circularly polarized radio pulses. Up to now, among the MCP stars only CU Virginis shows 100% polarized time-stable radio pulses, explained as highly directive electron cyclotron maser emission, visible from Earth at particular rotational phases, like a pulsar. Our analysis shows that there is no hint of coherent emission at frequencies below 15 GHz. We conclude that the presence of a quadrupolar component of the magnetic field, dominant within few stellar radii from the star, where the maser emission should be generated, inhibits the onset of the cyclotron maser instability in \sigma Ori E.
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    ABSTRACT: New data from the Herschel Infrared Galactic Plane Survey (Hi-GAL) and the Expanded Very Large Array, together with ancillary multifrequency data from different archives, have provided a comprehensive picture of the circumstellar envelope (CSE) surrounding the Galactic luminous blue variable (LBV) candidate Gal 026.47+0.02. The high angular resolution of both the 70-μm and 6-cm maps has allowed us to appreciate finest details of the nebula, whose morphology is consistent with a series of nested tori. The inner torus, which is close to the central object, is fully ionized, indicating events of aspherical mass loss. We have derived the physical properties of the CSE, including, in particular, one of the highest current-day mass losses from the central object and a very massive nebula, which consists of, at least, 17 M⊙ of ionized gas, with 1.2–3.2 × 10−2 M⊙ in the form of dust. Altogether, the physical properties of Gal 026.47+0.02, including a very high stellar luminosity, point towards a very massive progenitor on the main sequence. According to the current models for Type IIn supernovae, the CSEs associated with possible progenitors have well constrained properties in both content and morphology. The derived physical characteristics of the nebula associated with Gal 026.47+0.02 actually satisfy all such requirements, providing some observational evidence of a direct link between a LBV and a possible Type IIn supernova.
    The Astrophysical Journal Letters 08/2011; 739(1):L11. DOI:10.1088/2041-8205/739/1/L11 · 5.60 Impact Factor
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    ABSTRACT: Context. The blazar 3C 454.3 is one of the most active sources from the radio to the γ-ray frequencies observed in the past few years. Aims. We present multiwavelength observations of this source from April 2008 to March 2010. The radio to optical data are mostly from the GASP-WEBT, UV and X-ray data from Swift, and γ-ray data from the AGILE and Fermi satellites. The aim is to understand the connection among emissions at different frequencies and to derive information on the emitting jet. Methods. Light curves in 18 bands were carefully assembled to study flux variability correlations. We improved the calibration of optical–UV data from the UVOT and OM instruments and estimated the Lyα flux to disentangle the contributions from different components in this spectral region. Results. The observations reveal prominent variability above 8 GHz. In the optical–UV band, the variability amplitude decreases with increasing frequency due to a steadier radiation from both a broad line region and an accretion disc. The optical flux reaches nearly the same levels in the 2008–2009 and 2009–2010 observing seasons; the mm one shows similar behaviour, whereas the γ and X-ray flux levels rise in the second period. Two prominent γ-ray flares in mid 2008 and late 2009 show a double-peaked structure, with a variable γ/optical flux ratio. The X-ray flux variations seem to follow the γ-ray and optical ones by about 0.5 and 1 d, respectively. Conclusions. We interpret the multifrequency behaviour in terms of an inhomogeneous curved jet, where synchrotron radiation of increasing wavelength is produced in progressively outer and wider jet regions, which can change their orientation in time. In particular, we assume that the long-term variability is due to this geometrical effect. By combining the optical and mm light curves to fit the γ and X-ray ones, we find that the γ (X-ray) emission may be explained by inverse-Comptonisation of synchrotron optical (IR) photons by their parent relativistic electrons (SSC process). A slight, variable misalignment between the synchrotron and Comptonisation zones would explain the increased γ and X-ray flux levels in 2009–2010, as well as the change in the γ/optical flux ratio during the outbursts peaks. The time delays of the X-ray flux changes after the γ, and optical ones are consistent with the proposed scenario.
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    ABSTRACT: We have observed the radio nebula surrounding the Galactic LBV candidate G79.29+0.46 with the EVLA at 6 cm. These new radio observations allow a morphological comparison between the radio emission, which traces the ionized gas component, and the mid-IR emission, a tracer of the dust component. The IRAC (8 \mu m) and MIPS (24 \mu m and 70 \mu m) images have been reprocessed and compared with the EVLA map. We confirm the presence of a second shell at 24 \mu m and also provide evidence for its detection at 70 \mu m. The differences between the spatial morphology of the radio and mid-IR maps indicate the existence of two dust populations, the cooler one emitting mostly at longer wavelengths. Analysis of the two dusty, nested shells have provided us with an estimate of the characteristic timescales for shell ejection, providing important constraints for stellar evolutionary models. Finer details of the ionized gas distribution can be appreciated thanks to the improved quality of the new 6 cm image, most notably the highly structured texture of the nebula. Evidence of interaction between the nebula and the surrounding interstellar medium can be seen in the radio map, including brighter features that delineate regions where the shell structure is locally modified. In particular, the brighter filaments in the south-west region appear to frame the shocked southwestern clump reported from CO observations.
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    ABSTRACT: We present multiwavelength observations of the ultraluminous blazar-type radio loud quasar PKS 0528+134 in quiescence during the period 2009 July-December. Four Target-of-Opportunity observations with the XMM-Newton satellite in the 0.2-10 keV range were supplemented with optical observations at the MDM Observatory, radio and optical data from the GLAST-AGILE Support Program of the Whole Earth Blazar Telescope and the Very Long Baseline Array, additional X-ray data from the Rossi X-ray Timing Explorer (2-10 keV) and from Suzaku (0.5-10 keV) as well as γ-ray data from the Fermi Large Area Telescope in the 100 MeV-200 GeV range. In addition, publicly available data from the SMARTS blazar monitoring program and the University of Arizona/Steward Observatory Fermi Support program were included in our analysis. We found no evidence of significant flux or spectral variability in γ-rays and most radio bands. However, significant flux variability on a timescale of several hours was found in the optical regime, accompanied by a weak trend of spectral softening with increasing flux. We suggest that this might be the signature of a contribution of unbeamed emission, possibly from the accretion disk, at the blue end of the optical spectrum. The optical flux is weakly polarized with rapid variations of the degree and direction of polarization, while the polarization of the 43 GHz radio core remains steady, perpendicular to the jet direction. Optical spectropolarimetry of the object in the quiescent state suggests a trend of increasing degree of polarization with increasing wavelength, providing additional evidence for an unpolarized emission component, possibly thermal emission from the accretion disk, contributing toward the blue end of the optical spectrum. Over an extended period of several months, PKS 0528+134 shows moderate (amplitude 50%) flux variability in the X-rays and most radio frequencies on ~1-2 week timescales. We constructed four spectral energy distributions (SEDs) corresponding to the times of the XMM-Newton observations. We find that even in the quiescent state, the bolometric luminosity of PKS 0528+134 is dominated by its γ-ray emission. A leptonic single-zone jet model produced acceptable fits to the SEDs with contributions to the high-energy emission from both synchrotron self-Compton radiation and Comptonization of direct accretion disk emission. Fit parameters close to equipartition between the energy densities of the magnetic field and the relativistic electron population were obtained. The moderate variability on long timescales, compared to expected radiative cooling timescales, implies the existence of ongoing particle acceleration, while the observed optical polarization variability seems to point toward a turbulent acceleration process. Turbulent particle acceleration at stationary features along the jet therefore appears to be a viable possibility for the quiescent state of PKS 0528+134.
    The Astrophysical Journal 06/2011; 735(1):60. DOI:10.1088/0004-637X/735/1/60 · 6.28 Impact Factor
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    ABSTRACT: CU Virginis is a rapidly rotating Magnetic Chemically Peculiar star with at present unique characteristics as radio emitter. The most intriguing one is the presence of intense, 100% circularly polarized radiation ascribed to Cyclotron Maser. Each time the star rotates, this highly beamed emission points two times toward the Earth, like a pulsar. We observed CU Vir in April 2010 with the EVLA in two bands centered at 1450 and 1850 MHz. We covered nearly the whole rotational period, confirming the presence of the two pulses at a flux density up to 20 mJy. Dynamical spectra, obtained with unprecedented spectral and temporal sensitivity, allow us to clearly see the different time delays as a function of the frequency. We interpret this behaviour as a propagation effect of the radiation inside the stellar magnetosphere. The emerging scenario suggests interesting similarities with the auroral radio emission from planets, in particular with the Auroral Kilometric Radiation (AKR) from Earth, which originates at few terrestrial radii above the magnetic poles and was only recently discovered to be highly beamed. We conclude that the magnetospheres of CU Vir, Earth and other planets, maybe also exoplanets, could have similar geometrical and physical characteristics in the regions where the cyclotron maser is generated. In addition, the pulses are perfect "markers" of the rotation period. This has given us for the first time the possibility to measure with extraordinary accuracy the spin down of a star on or near the main sequence.
    The Astrophysical Journal Letters 04/2011; 739(1). DOI:10.1088/2041-8205/739/1/L10 · 5.60 Impact Factor

Publication Stats

964 Citations
316.76 Total Impact Points

Institutions

  • 2012
    • Boston University
      • Institute for Astrophysical Research
      Boston, Massachusetts, United States
  • 2010
    • Harvard-Smithsonian Center for Astrophysics
      Cambridge, Massachusetts, United States
    • Pennsylvania State University
      • Department of Astronomy and Astrophysics
      University Park, Maryland, United States
  • 2007
    • Saint Petersburg State University
      Sankt-Peterburg, St.-Petersburg, Russia
  • 2006
    • National Institute of Astrophysics
      • Institute of Space Astrophysics and Cosmic Physics IASF - Rome
      Roma, Latium, Italy
  • 1999
    • Università degli Studi di Messina
      Messina, Sicily, Italy