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Sean M. Moran,
Timothy M. Heckman,
Guinevere Kauffmann,
Romeel Davé,
Barbara Catinella,
Jarle Brinchmann,
Jing Wang,
David Schiminovich,
Amélie Saintonge,
Javier Gracia-Carpio, Linda Tacconi,
Riccardo Giovanelli,
Martha Haynes,
Silvia Fabello,
Cameron Hummels,
Jenna Lemonias,
and Ronin Wu
[show abstract]
[hide abstract]
ABSTRACT: We have obtained long-slit spectra of 174 star-forming galaxies with stellar masses greater than 1010 M ☉ from the GALEX Arecibo Sloan Digital Sky Survey (GASS) survey. These galaxies have both H I and H2 mass measurements. The average metallicity profile is strikingly flat out to R 90, the radius enclosing 90% of the r-band light. Metallicity profiles which decline steadily with radius are found primarily for galaxies in our sample with low stellar mass (log(M *) < 10.2), concentration, and/or mean stellar mass density. Beyond ~R 90, however, around 10% of the galaxies in our sample exhibit a sharp downturn in metallicity. Remarkably, we find that the magnitude of the outer metallicity drop is well correlated with the total H I content of the galaxy (measured as f H I = M H I /M *). We examine the radial profiles of stellar population ages and star formation rate densities, and conclude that the galaxies with largest outer metallicity drops are actively growing their stellar disks, with mass-doubling times across the whole disk only one-third as long as a typical GASS galaxy. We also describe a correlation between local stellar mass density and metallicity, which is valid across all galaxies in our sample. We argue that much of the recent stellar mass growth at the edges of these galaxies can be linked to the accretion or radial transport of relatively pristine gas from beyond the galaxies' stellar disks.
The Astrophysical Journal 12/2011; 745(1):66. · 6.02 Impact Factor
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Stijn Wuyts,
Natascha M. Forster Schreiber,
Arjen van der Wel,
Benjamin Magnelli,
Yicheng Guo,
Reinhard Genzel,
Dieter Lutz,
Herve Aussel,
Guillermo Barro,
Stefano Berta, [......],
Kyoung-Soo Lee,
Emeric Le Floc'h,
Elizabeth J. McGrath,
Raanan Nordon,
Paola Popesso,
Francesca Pozzi,
Laurie Riguccini,
Giulia Rodighiero,
Amelie Saintonge, Linda Tacconi
[show abstract]
[hide abstract]
ABSTRACT: We analyze the dependence of galaxy structure (size and Sersic index) and
mode of star formation (\Sigma_SFR and SFR_IR/SFR_UV) on the position of
galaxies in the SFR versus Mass diagram. Our sample comprises roughly 640000
galaxies at z~0.1, 130000 galaxies at z~1, and 36000 galaxies at z~2.
Structural measurements for all but the z~0.1 galaxies were based on HST
imaging, and SFRs are derived using a Herschel-calibrated ladder of SFR
indicators. We find that a correlation between the structure and stellar
population of galaxies (i.e., a 'Hubble sequence') is already in place since at
least z~2.5. At all epochs, typical star-forming galaxies on the main sequence
are well approximated by exponential disks, while the profiles of quiescent
galaxies are better described by de Vaucouleurs profiles. In the upper envelope
of the main sequence, the relation between the SFR and Sersic index reverses,
suggesting a rapid build-up of the central mass concentration in these
starbursting outliers. We observe quiescent, moderately and highly star-forming
systems to co-exist over an order of magnitude or more in stellar mass. At each
mass and redshift, galaxies on the main sequence have the largest size. The
rate of size growth correlates with specific SFR, and so does \Sigma_SFR at
each redshift. A simple model using an empirically determined SF law and
metallicity scaling, in combination with an assumed geometry for dust and stars
is able to relate the observed \Sigma_SFR and SFR_IR/SFR_UV, provided a more
patchy dust geometry is assumed for high-redshift galaxies.
07/2011;
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Stijn Wuyts,
Natascha M. Forster Schreiber,
Dieter Lutz,
Raanan Nordon,
Stefano Berta,
Bruno Altieri,
Paola Andreani,
Herve Aussel,
Angel Bongiovanni,
Jordi Cepa, [......],
Roberto Maiolino,
Elizabeth J. McGrath,
Ana Perez Garcia,
Albrecht Poglitsch,
Paola Popesso,
Francesca Pozzi,
Miguel Sanchez-Portal,
Eckhard Sturm, Linda Tacconi,
Ivan Valtchanov
[show abstract]
[hide abstract]
ABSTRACT: We compare multi-wavelength SFR indicators out to z~3 in GOODS-South. Our
analysis uniquely combines U-to-8um photometry from FIREWORKS, MIPS 24um and
PACS 70, 100, and 160um photometry from the PEP survey, and Ha spectroscopy
from the SINS survey. We describe a set of conversions that lead to a
continuity across SFR indicators. A luminosity-independent conversion from 24um
to total infrared luminosity yields estimates of LIR that are in the median
consistent with the LIR derived from PACS photometry, albeit with significant
scatter. Dust correction methods perform well at low to intermediate levels of
star formation. They fail to recover the total amount of star formation in
systems with large SFR_IR/SFR_UV ratios, typically occuring at the highest SFRs
(SFR_UV+IR \gtrsim 100 Msun/yr) and redshifts (z \gtrsim 2.5) probed. Finally,
we confirm that Ha-based SFRs at 1.5<z<2.6 are consistent with SFR_SED and
SFR_UV+IR provided extra attenuation towards HII regions is taken into account
(Av,neb = Av,continuum / 0.44). With the cross-calibrated SFR indicators in
hand, we perform a consistency check on the star formation histories inferred
from SED modeling. We compare the observed SFR-M relations and mass functions
at a range of redshifts to equivalents that are computed by evolving lower
redshift galaxies backwards in time. We find evidence for underestimated
stellar ages when no stringent constraints on formation epoch are applied. We
demonstrate how resolved SED modeling, or alternatively deep UV data, may help
to overcome this bias. The age bias is most severe for galaxies with young
stellar populations, and reduces towards older systems. Finally, our analysis
suggests that SFHs typically vary on timescales that are long (at least several
100 Myr) compared to the galaxies' dynamical time.
06/2011;
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Sean M. Moran,
Guinevere Kauffmann,
Timothy M. Heckman,
Javier Gracia-Carpio,
Amelie Saintonge,
Barbara Catinella,
Jing Wang,
Yan-Mei Chen, Linda Tacconi,
David Schiminovich,
Pierre Cox,
Riccardo Giovanelli,
Martha Haynes,
and Carsten Kramer
[show abstract]
[hide abstract]
ABSTRACT: We report new observations of the galaxy UGC8802 obtained through the GALEX Arecibo SDSS Survey (GASS), which show this galaxy to be in a remarkable evolutionary state. UGC8802 (GASS35981) is a disk galaxy with stellar mass M * = 2 × 1010 M ☉, which appears to contain an additional 2.1 × 1010 M ☉ of H I gas. New millimeter observations with the IRAM 30 m telescope indicate a molecular gas mass only a tenth this large. Using deep long-slit spectroscopy, we examine the spatially resolved star formation rate (SFR) and metallicity profiles of GASS35981 for clues to its history. We find that the star formation surface density in this galaxy is low (ΣSFR = 0.003 M ☉ yr–1 kpc–2) and that the star formation is spread remarkably evenly across the galaxy. The low molecular gas masses measured in our three IRAM pointings are largely consistent with the total star formation measured within the same apertures. Our MMT long-slit spectrum reveals a sharp drop in metallicity in the outer disk of GASS35981. The ratio of current SFR to existing stellar mass surface density in the outer disk is extremely high, implying that all the stars must have formed within the past ~1 Gyr. At current SFRs, however, GASS35981 will not consume its H I reservoir for another 5-7 Gyr. Despite its exceptionally large gas fraction for a galaxy this massive, GASS35981 has a regular rotation curve and exhibits no sign of a recent interaction or merger. We speculate that GASS35981 may have acquired its gas directly from the intergalactic medium, and that GASS35981 and other similar galaxies identified in the GASS survey may provide rare local glimpses of gas accretion processes that were more common during the prime epoch of disk galaxy formation at z ~ 1.
The Astrophysical Journal 08/2010; 720(2):1126. · 6.02 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We describe several projects addressing the growth of galaxies and massive black holes, for which adaptive optics is mandatory to reach high spatial resolution but is also a challenge due to the lack of guide stars and long integrations. In each case kinematics of the stars and gas, derived from integral field spectroscopy, plays a key role. We explain why deconvolution is not an option, and that instead the PSF is used to convolve a physical model to the required resolution. We discuss the level of detail with which the PSF needs to be known, and the ways available to derive it. We explain how signal-to-noise can limit the resolution achievable and show there are many science cases that require high, but not necessarily diffraction limited, resolution. Finally, we consider what requirements astrometry and photometry place on adaptive optics performance and design. Comment: Contribution to "Adaptive Optics Systems II", SPIE 7736-51 (June 2010). High resolution version can be found at http://spiedl.org
05/2010;
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Jacqueline Fischer,
Eckhard Sturm,
Eduardo González-Alfonso,
Javier Graciá-Carpio,
Steve Hailey-Dunsheath,
Albrecht Poglitsch,
Alessandra Contursi,
Dieter Lutz,
Reinhard Genzel,
Amiel Sternberg,
Aprajita Verma, Linda Tacconi
[show abstract]
[hide abstract]
ABSTRACT: In this first paper on the results of our Herschel PACS survey of local Ultraluminous Infrared Galaxies (ULIRGs), as part of our SHINING survey of local galaxies, we present far-infrared spectroscopy of Mrk 231, the most luminous of the local ULIRGs, and a type 1 broad absorption line AGN. For the first time in a ULIRG, all observed far-infrared fine-structure lines in the PACS range were detected and all were found to be deficient relative to the far infrared luminosity by 1 - 2 orders of magnitude compared with lower luminosity galaxies. The deficits are similar to those for the mid-infrared lines, with the most deficient lines showing high ionization potentials. Aged starbursts may account for part of the deficits, but partial covering of the highest excitation AGN powered regions may explain the remaining line deficits. A massive molecular outflow, discovered in OH and 18OH, showing outflow velocities out to at least 1400 km/sec, is a unique signature of the clearing out of the molecular disk that formed by dissipative collapse during the merger. The outflow is characterized by extremely high ratios of 18O / 16O suggestive of interstellar medium processing by advanced starbursts. Comment: Accepted for publication in the Astronomy and Astrophysics Herschel Special Issue, 5 pages, 4 figures
05/2010;
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Kristen L. Shapiro,
Reinhard Genzel,
Eliot Quataert,
Natascha M. Förster Schreiber,
Richard Davies, Linda Tacconi,
Lee Armus,
Nicolas Bouché,
Peter Buschkamp,
Andrea Cimatti, [......],
Frank Eisenhauer,
Dawn K. Erb,
Shy Genel,
Erin K. S. Hicks,
Simon J. Lilly,
Dieter Lutz,
Alvio Renzini,
Alice Shapley,
Charles C. Steidel,
and Amiel Sternberg
[show abstract]
[hide abstract]
ABSTRACT: High signal-to-noise, representative spectra of star-forming galaxies at z ~ 2, obtained via stacking, reveal a high-velocity component underneath the narrow Hα and [N II] emission lines. When modeled as a single Gaussian, this broad component has FWHM 1500 km s–1; when modeled as broad wings on the Hα and [N II] features, it has FWHM 500 km s–1. This feature is preferentially found in the more massive and more rapidly star-forming systems, which also tend to be older and larger galaxies. We interpret this emission as evidence of either powerful starburst-driven galactic winds or active supermassive black holes (SMBHs). If galactic winds are responsible for the broad emission, the observed luminosity and velocity of this gas imply mass outflow rates comparable to the star formation rate. On the other hand, if the broad-line regions of active black holes account for the broad feature, the corresponding black holes masses are estimated to be an order of magnitude lower than those predicted by local scaling relations, suggesting a delayed assembly of SMBHs with respect to their host bulges.
The Astrophysical Journal 07/2009; 701(2):955. · 6.02 Impact Factor
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Kristen L. Shapiro,
Reinhard Genzel,
Nicolas Bouché,
Peter Buschkamp,
Giovanni Cresci,
Ric Davies,
Frank Eisenhauer,
Natascha Förster Schreiber,
Shy Genel,
Erin Hicks,
Dieter Lutz, Linda Tacconi
[show abstract]
[hide abstract]
ABSTRACT: In these proceedings, we summarize recent results from our "SINS" VLT/SINFONI integral-field survey, focusing on the 52 detected UV/optically-selected star-forming galaxies at z~2. Our H-alpha emission-line imaging and kinematic data of these systems illustrates that a substantial fraction (> 1/3) of these galaxies are large, rotating disks and that these disks are clumpy, thick, and forming stars rapidly. We compare these systems to local disk scaling relations and find that the backbones of these relations are already in place at z~2. Detailed analysis of the large disks in our sample provides strong evidence that this population cannot result from a merger-dominated formation history and instead must be assembled by the smooth but rapid inflow of gas along filaments. These systems will then secularly evolve from clump-dominated disks to bulge-dominated disks on short timescales, a phenomenon that is observed in our SINS observations and is consistent with predictions from numerical simulations. These results provide new and exciting insights into the formation of bulge-dominated galaxies in the local Universe.
03/2009;
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Carol J. Lonsdale,
Maria del Carmen Polletta,
Alain Omont,
Dave Shupe,
Stefano Berta,
Robert Zylka,
Brian Siana,
Dieter Lutz,
Duncan Farrah,
Harding E. Smith, [......],
Frazer Owen,
Alexandre Beelen,
Dan Weedman,
Alberto Franceschini,
Dave Clements, Linda Tacconi,
Alejandro Afonso-Luis,
Ismael Pérez-Fournon,
Pierre Cox,
and Frank Bertoldi
[show abstract]
[hide abstract]
ABSTRACT: We report on-off pointed MAMBO observations at 1.2 mm of 61 Spitzer-selected star-forming galaxies from the Spitzer Wide Area Infrared Extragalactic Legacy survey (SWIRE). The sources are selected on the basis of bright 24 μm fluxes (f 24 μm > 0.4 mJy) and of stellar dominated near-infrared spectral energy distributions in order to favor z ~ 2 starburst galaxies. The average 1.2 mm flux for the whole sample is 1.5 ± 0.2 mJy. Our analysis focuses on 29 sources in the Lockman Hole field where the average 1.2 mm flux (1.9 ± 0.3 mJy) is higher than in other fields (1.1 ± 0.2 mJy). The analysis of the multiwavelength spectral energy distributions indicates that these sources are starburst galaxies with far-infrared luminosities from 1012 to 1013.3 L ☉, and stellar masses of ~0.2-6 × 1011 M ☉. Compared to submillimeter selected galaxies (SMGs), the SWIRE-MAMBO sources are among those with the largest 24 μm/1.2 mm flux ratios. The origin of such large ratios is investigated by comparing the average mid-infrared spectra and the stacked far-infrared spectral energy distributions of the SWIRE-MAMBO sources and of SMGs. The mid-infrared spectra, available for a handful of sources, exhibit strong polycyclic aromatic hydrocarbon (PAH) features, and a warm dust continuum. The warm dust continuum contributes ~34% of the mid-infrared emission, and is likely associated with an AGN component. This contribution is consistent with what is found in SMGs. The large 24 μm/1.2 mm flux ratios are thus not due to AGN emission, but rather to enhanced PAH emission compared to SMGs. The analysis of the stacked far-infrared fluxes yields warmer dust temperatures than typically observed in SMGs. Our selection favors warm ultraluminous infrared sources at high-z, a class of objects that is rarely found in SMG samples. Indeed SMGs are not common among bright 24 μm sources (e.g., only about 20% of SMGs have f 24 μm > 0.4 mJy). Our sample is the largest Spitzer-selected sample detected at millimeter wavelengths currently available.
The Astrophysical Journal 02/2009; 692(1):422. · 6.02 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We present the FIR, millimeter, and radio photometry and optical and NIR spectroscopy of a sample of 48 z ~ 1–3 Spitzer-selected ULIRGs with IRS MIR spectra. Our goals are to compute their bolometric emission and to determine both the presence and relative strength of their AGN and starburst components. We find that strong-PAH sources tend to have higher MIPS 160 μm and MAMBO 1.2 mm fluxes than weak-PAH sources. The depth of the 9.7 μm silicate feature does not affect MAMBO detectability. We fit the far-IR SEDs of our sample and find an average LIR ~ 7 × 1012 L☉ for our z > 1.5 sources. Our spectral decomposition suggests that strong-PAH sources typically have ~20%-30% AGN fractions of LIR. The weak-PAH sources by contrast tend to have 70% AGN fractions, with a few sources having comparable contributions of AGN and starbursts. The optical line diagnostics support the presence of AGNs in the bulk of the weak-PAH sources. With one exception, our sources are narrow-line sources, show no obvious correspondence between the available optical extinction and the silicate feature depth, and, in two cases, show some evidence for outflows. Radio AGNs are present in both strong- and weak-PAH sources. This is supported by our sample's FIR-to-radio ratios (q) being consistently below the average value of 2.34 for local star-forming galaxies. We use survival analysis to include the lower limits given by the radio-undetected sources, arriving at q = 2.07 ± 0.01 for our z > 1.5 sample. In total, radio and, where available, optical line diagnostics support the presence of AGNs in 57% of the z > 1.5 sources, independent of IR-based diagnostics. For higher z sources, the AGN luminosities alone are estimated to be >1012 L☉, which, supported by the available [O III] luminosities, implies that the bulk of our sources host obscured quasars.
The Astrophysical Journal 12/2008; 683(2):659. · 6.02 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We present the far-IR, millimeter, and radio photometry as well as optical and near-IR spectroscopy of a sample of 48 z~1-3 Spitzer-selected ULIRGs with IRS mid-IR spectra. Our goals are to compute their bolometric emission, and to determine both the presence and relative strength of their AGN and starburst components. We find that strong-PAH sources tend to have higher 160um and 1.2mm fluxes than weak-PAH sources. The depth of the 9.7um silicate feature does not affect MAMBO detectability. We fit the far-IR SEDs of our sample and find an average <L_{IR}>~7x10^{12}Lsun for our z>1.5 sources. Spectral decomposition suggests that strong-PAH sources typically have ~20-30% AGN fractions. Weak-PAH sources by contrast tend to have >~70% AGN fractions, with a few sources having comparable contributions of AGN and starbursts. The optical line diagnostics support the presence of AGN in the bulk of the weak-PAH sources. With one exception, our sources are narrow-line sources, show no obvious correspondence between the optical extinction and the silicate feature depth, and, in two cases, show evidence for outflows. Radio AGN are present in both strong-PAH and weak-PAH sources. This is supported by our sample's far-IR-to-radio ratios (q) being consistently below the average value of 2.34 for local star-forming galaxies. We use survival analysis to include the lower-limits given by the radio-undetected sources, arriving at =2.07+/-0.01 for our z>1.5 sample. In total, radio and, where available, optical line diagnostics support the presence of AGN in 57% of the z>1.5 sources, independent of IR-based diagnostics. For higher-z sources, the AGN luminosities alone are estimated to be >10^{12}Lsun, which, supported by the [OIII] luminosities, implies that the bulk of our sources host obscured quasars. Comment: 22 pages, 14 figures, accepted for publication in ApJ
05/2008;
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[show abstract]
[hide abstract]
ABSTRACT: Low-ionization transitions such as the MgII 2796/2803 doublet trace cold gas in the vicinity of galaxies. It is not clear whether this gas is part of the interstellar medium of large proto-disks, part of dwarfs, or part of entrained material in supernovae-driven outflows. Studies based on MgII statistics, e.g. stacked images and clustering analysis, have invoked starburst-driven outflows where MgII absorbers are tracing the denser and colder gas of the outflow. A consequence of the outflow scenario is that the strongest absorbers ought to be associated with starbursts. We use the near-IR integral field spectrograph SINFONI to test whether starbursts are found around z~1 MgII absorbers. For 67% (14 out of 21) of the absorbers with rest-frame equivalent width larger than 2 AA, we do detect Ha in emission within 200 km/s of the predicted wavelength based on the \MgII redshift. The star-formation rate (SFR) inferred from Halpha ranges from 1 to 20 Msun/yr, i.e. showing a level of star-formation larger than in M82 by a factor of >4 on average. Our flux limit (3-sigma) corresponds to a SFR of 0.5 Msun/yr. We find evidence (at >95% confidence) for a correlation between SFR and equivalent width, indicating a physical connection between starburst phenomena and gas seen in absorption. In the cases where we can extract the velocity field, the host-galaxies reside in halos with mean mass =11.2 in good agreement with clustering measurements. Comment: 4 pages, 3 figures, accepted for publication in ApJ Letters, minor typos corrected to match proofs
09/2007;
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[show abstract]
[hide abstract]
ABSTRACT: We are using adaptive optics on Keck and the VLT to probe the dynamics and star formation in Seyfert and QSO nuclei, obtaining
spatial resolutions better than 0.1 in the H- and K-bands. The dynamics are traced via the 2.12 H2 1-0 S(1) line, while the stellar cluster is traced through the CO 2-0 and 6-3 absorption bandheads at 2.29 and 1.62 respectively.
Matching disk models to the H2 rotation curves allows us to study nuclear rings, bars, and warps; and to constrain the mass of the central black hole. The
spatial extent and equivalent width of the stellar absorption permits us to estimate the mass of stars in the nucleus and
their contribution to the emission. Here we report on new data for I Zwicky 1, Markarian 231, and NGC 7469.
12/2005: pages 291-297;
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[show abstract]
[hide abstract]
ABSTRACT: It is becoming increasingly clear that collisions between galaxies play an important role in galaxy evolution. The ultraluminous infrared galaxies are predominantly powered by enormous star-formation events that are triggered in the last phases of such collisions. These bursts occur just before the galaxies merge to form single elliptical galaxies.
Nature 10/1998; 395(6705):859-869. · 36.28 Impact Factor
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Henri Bonnet,
Roberto Abuter,
Andrew Baker,
Walter Bornemann,
Anthony Brown,
Roberto Castillo,
Ralph Conzelmann,
Romuald Damster,
Richard Davies,
Bernard Delabre, [......],
Ton Schoenmaker,
Jürgen Schreiber,
Stefan Ströbele,
Thomas Szeifert, Linda Tacconi,
Matthias Tecza,
Niranjan Thatte,
Sebastien Tordo,
Paul van der Werf,
Harald Weisz
The ESO Messenger, v.117, 17-24 (2004).
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http://dx.doi.org/10.1051/0004-6361/201015338.
