HERSCHEL-ATLAS GALAXY COUNTS AND HIGH-REDSHIFT LUMINOSITY FUNCTIONS: THE FORMATION OF MASSIVE EARLY-TYPE GALAXIES
- Dipartimento di Fisica, Universita 'Tor Vergata', Via della Ricerca Scientifica 1, 00133 Roma (Italy)
- Astrophysics Sector, SISSA, Via Bonomea 265, 34136 Trieste (Italy)
- Department of Physics and Astronomy, Open University, Milton Keynes MK7 6AA (United Kingdom)
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)
- School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom)
- Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium)
- Centre for Astrophysics, University of Hertfordshire, Hatfield, Herts AL10 9AB (United Kingdom)
- INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova (Italy)
- Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)
- Astrophysics Group, Imperial College, Blackett Lab, Prince Consort Road, London SW7 2AZ (United Kingdom)
- Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)
Exploiting the Herschel Astrophysical Terahertz Large Area Survey Science Demonstration Phase survey data, we have determined the luminosity functions (LFs) at rest-frame wavelengths of 100 and 250 {mu}m and at several redshifts z {approx}> 1, for bright submillimeter galaxies with star formation rates (SFRs) {approx}> 100 M{sub Sun} yr{sup -1}. We find that the evolution of the comoving LF is strong up to z Almost-Equal-To 2.5, and slows down at higher redshifts. From the LFs and the information on halo masses inferred from clustering analysis, we derived an average relation between SFR and halo mass (and its scatter). We also infer that the timescale of the main episode of dust-enshrouded star formation in massive halos (M{sub H} {approx}> 3 Multiplication-Sign 10{sup 12} M{sub Sun }) amounts to {approx}7 Multiplication-Sign 10{sup 8} yr. Given the SFRs, which are in the range of 10{sup 2}-10{sup 3} M{sub Sun} yr{sup -1}, this timescale implies final stellar masses of the order of 10{sup 11}-10{sup 12} M{sub Sun }. The corresponding stellar mass function matches the observed mass function of passively evolving galaxies at z {approx}> 1. The comparison of the statistics for submillimeter and UV-selected galaxies suggests that the dust-free, UV bright phase is {approx}> 10{sup 2} times shorter than the submillimeter bright phase, implying that the dust must form soon after the onset of star formation. Using a single reference spectral energy distribution (SED; the one of the z Almost-Equal-To 2.3 galaxy SMM J2135-0102), our simple physical model is able to reproduce not only the LFs at different redshifts >1 but also the counts at wavelengths ranging from 250 {mu}m to Almost-Equal-To 1 mm. Owing to the steepness of the counts and their relatively broad frequency range, this result suggests that the dispersion of submillimeter SEDs of z > 1 galaxies around the reference one is rather small.
- OSTI ID:
- 21612645
- Journal Information:
- Astrophysical Journal, Vol. 742, Issue 1; Other Information: DOI: 10.1088/0004-637X/742/1/24; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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