THE COMPLEX PHYSICS OF DUSTY STAR-FORMING GALAXIES AT HIGH REDSHIFTS AS REVEALED BY HERSCHEL AND SPITZER

Journal Article · Thu Jan 10 00:00:00 EST 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/762/2/108· OSTI ID:22167263

Lo Faro, B.; Franceschini, A.; Vaccari, M.; Rodighiero, G.; Feltre, A.; Marchetti, L. ^[1]; Silva, L. ^[2]; Berta, S.; Lutz, D.; Magnelli, B. ^[3]; Bock, J. ^[4]; Burgarella, D.; Buat, V. ^[5]; Cava, A. ^[6]; Clements, D. L. ^[7]; Cooray, A. ^[8]; Farrah, D.; Hurley, P. ^[9]; Solares, E. A. Gonzalez ^[10]; others, and

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1. Dipartimento di Fisica e Astronomia, Universita di Padova, vicolo Osservatorio, 3, I-35122 Padova (Italy)
2. INAF-OATs, Via Tiepolo 11, I-34131 Trieste (Italy)
3. MPE, Postfach 1312, D-85741, Garching (Germany)
4. California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States)
5. Laboratoire d'Astrophysique de Marseille, OAMP, Universite Aix-Marseille, CNRS, 38 rue Frederic Joliot-Curie, F-13388 Marseille Cedex 13 (France)
6. Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)
7. Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)
8. Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)
9. Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom)
10. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

We combine far-infrared photometry from Herschel (PEP/HerMES) with deep mid-infrared spectroscopy from Spitzer to investigate the nature and the mass assembly history of a sample of 31 luminous and ultraluminous infrared galaxies ((U)LIRGs) at z {approx} 1 and 2 selected in GOODS-S with 24 {mu}m fluxes between 0.2 and 0.5 mJy. We model the data with a self-consistent physical model (GRASIL) which includes a state-of-the-art treatment of dust extinction and reprocessing. We find that all of our galaxies appear to require massive populations of old (>1 Gyr) stars and, at the same time, to host a moderate ongoing activity of star formation (SFR {<=} 100 M {sub Sun} yr{sup -1}). The bulk of the stars appear to have been formed a few Gyr before the observation in essentially all cases. Only five galaxies of the sample require a recent starburst superimposed on a quiescent star formation history. We also find discrepancies between our results and those based on optical-only spectral energy distribution (SED) fitting for the same objects; by fitting their observed SEDs with our physical model we find higher extinctions (by {Delta}A {sub V} {approx} 0.81 and 1.14) and higher stellar masses (by {Delta}log(M {sub *}) {approx} 0.16 and 0.36 dex) for z {approx} 1 and z {approx} 2 (U)LIRGs, respectively. The stellar mass difference is larger for the most dust-obscured objects. We also find lower SFRs than those computed from L {sub IR} using the Kennicutt relation due to the significant contribution to the dust heating by intermediate-age stellar populations through 'cirrus' emission ({approx}73% and {approx}66% of the total L {sub IR} for z {approx} 1 and z {approx} 2 (U)LIRGs, respectively).

• OSTI ID: 22167263
• Journal Information: Astrophysical Journal, Vol. 762, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABSORPTION SPECTROSCOPY
ASTRONOMY
ASTROPHYSICS
COSMIC DUST
ENERGY SPECTRA
GALACTIC EVOLUTION
GALAXIES
INFRARED SPECTRA
INTERMEDIATE INFRARED RADIATION
MASS
PHOTOMETRY
PHOTON EMISSION
RED SHIFT
STAR MODELS
STARS