Identification of z ≳ 2 Herschel 500 μm sources using color deconfusion

Journal Article · Thu Dec 31 23:00:00 EST 2015 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.3847/0067-0049/222/1/4· OSTI ID:22872396

Shu, X. W.; Elbaz, D.; Schreiber, C.; Wang, T.; Pannella, M.; Okumura, K. ^[1]; Bourne, N.; Dunlop, J. S.; Michałowski, M. J.; Buitrago, F.; Bruce, V. A. ^[2]; Fontana, A.; Santini, P.; Merlin, E.; Amorin, R.; Castellano, M. ^[3]; Leiton, R. ^[4]; Derriere, S. ^[5]; Comastri, A.; others, and

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1. Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu—CNRS—Université Paris Diderot, CEA-Saclay, pt courrier 131, F-91191 Gif-sur-Yvette (France)
2. SUPA, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, EH9 3HJ (United Kingdom)
3. INAF—Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio Catone (RM) (Italy)
4. Astronomy Department, Universidad de Concepción, Casilla 160-C, Concepcin (Chile)
5. Observatoire astronomique de Strasbourg, Universit de Strasbourg, CNRS, UMR 7550, 11 rue de lUniversit, F-67000 Strasbourg (France)

We present a new method to search for candidate z ≳ 2 Herschel 500 μm sources in the Great Observatories Origins Deep Survey-North field using a S{sub 500 μm}/S{sub 24 μm} “color deconfusion” technique. Potential high-z sources are selected against low-redshift ones from their large 500 to 24 μm flux density ratios. By effectively reducing the contribution from low-redshift populations to the observed 500 μm emission, we are able to identify counterparts to high-z 500 μm sources whose 24 μm fluxes are relatively faint. The recovery of known z ≳ 4 starbursts confirms the efficiency of this approach in selecting high-z Herschel sources. The resulting sample consists of 34 dusty star-forming galaxies at z ≳ 2. The inferred infrared luminosities are in the range 1.5 × 10{sup 12}–1.8 × 10{sup 13} L{sub ⊙}, corresponding to dust-obscured star formation rates (SFRs) of ∼260–3100 M{sub ⊙} yr{sup −1} for a Salpeter initial mass function. Comparison with previous SCUBA 850 μm-selected galaxy samples shows that our method is more efficient at selecting high-z dusty galaxies, with a median redshift of z=3.07±0.83 and with 10 of the sources at z ≳ 4. We find that at a fixed luminosity, the dust temperature is ∼5 K cooler than that expected from the T{sub d}−L{sub IR} relation at z ≲ 1, though different temperature selection effects should be taken into account. The radio-detected subsample (excluding three strong active galactic nucleus) follows the far-infrared (far-IR)/radio correlation at lower redshifts, and no evolution with redshift is observed out to z∼5, suggesting that the far-IR emission is star formation dominated. The contribution of the high-z Herschel 500 μm sources to the cosmic SFR density is comparable to that of (sub)millimeter galaxy populations at z∼2.5 and at least 40% of the extinction-corrected UV samples at z∼4. Further investigation into the nature of these high-z dusty galaxies will be crucial for our understanding of the star formation histories and the buildup of stellar mass at the earliest cosmic epochs.

• OSTI ID: 22872396
• Journal Information: Astrophysical Journal, Supplement Series, Journal Name: Astrophysical Journal, Supplement Series Journal Issue: 1 Vol. 222; ISSN 0067-0049; ISSN APJSA2
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COLOR
COSMIC DUST
EMISSION
FLUX DENSITY
GALAXIES
GALAXY NUCLEI
LUMINOSITY
RED SHIFT
STARS