Infrared color selection of massive galaxies atz > 3

Journal Article · Sun Jan 10 04:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/816/2/84· OSTI ID:22879401

Wang, T.; Elbaz, D.; Schreiber, C.; Pannella, M.; Daddi, E.; Ciesla, L.; Juneau, S. ^[1]; Shu, X. ^[2]; Willner, S. P.; Ashby, M. L. N.; Huang, J. -S. ^[3]; Fontana, A.; Boutsia, K. ^[4]; Dekel, A. ^[5]; Ferguson, H. C.; Koekemoer, A. M. ^[6]; Dunlop, J. ^[7]; Giavalisco, M. ^[8]; Finkelstein, S. ^[9]; others, and

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1. Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu, F-91191 Gif-sur-Yvette (France)
2. Department of Physics, Anhui Normal University, Wuhu, Anhui, 241000 (China)
3. Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)
4. INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio Catone (Italy)
5. Center for Astrophysics and Planetary Science, Racah Institute of Physics,The Hebrew University, Jerusalem, 91904 (Israel)
6. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
7. SUPA, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, EH9 3HJ (United Kingdom)
8. Department of Astronomy, University of Massachusetts, Amherst, MA (United States)
9. Department of Astronomy, The University of Texas at Austin, Austin, TX 78712 (United States)

We introduce a new color selection technique to identify high-redshift, massive galaxies that are systematically missed by Lyman-break selection. The new selection is based on the H{sub 160} (H) and Infrared Array Camera (IRAC) 4.5 μm bands, specifically H−[4.5]>2.25 mag. These galaxies, called “HIEROs,” include two major populations that can be separated with an additional J − H color. The populations are massive and dusty star-forming galaxies at z>3 (JH−blue) and extremely dusty galaxies at z≲3 (JH−red). The 350 arcmin{sup 2} of the GOODS-North and GOODS-South fields with the deepest Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) near-infrared and IRAC data contain as many as 285 HIEROs down to [4.5]<24 mag. Inclusion of the most extreme HIEROs, not even detected in the H band, makes this selection particularly complete for the identification of massive high-redshift galaxies. We focus here primarily on JH−blue (z>3) HIEROs, which have a median photometric redshift 〈z〉∼4.4 and stellar mass M{sub ∗}∼10{sup 10.6} M{sub ⊙} and are much fainter in the rest-frame UV than similarly massive Lyman-break galaxies (LBGs). Their star formation rates (SFRs), derived from their stacked infrared spectral energy distributions (SEDs), reach ∼240 M{sub ⊙} yr{sup −1}, leading to a specific SFR, sSFR≡SFR/M{sub ∗}∼4.2 Gyr{sup −1}, suggesting that the sSFRs for massive galaxies continue to grow at z>2 but at a lower growth rate than from z = 0 to z = 2. With a median half-light radius of 2 kpc, including ∼20% as compact as quiescent (QS) galaxies at similar redshifts, JH−blue HIEROs represent perfect star-forming progenitors of the most massive (M{sub ∗}≳10{sup 11.2} M{sub ⊙}) compact QS galaxies at z∼3 and have the right number density. HIEROs make up ∼60% of all galaxies with M{sub ∗}>10{sup 10.5} M{sub ⊙} identified at z>3 from their photometric redshifts. This is five times more than LBGs with nearly no overlap between the two populations. While HIEROs make up 15%–25% of the total SFR density at z∼4–5, they completely dominate the SFR density taking place in M{sub ∗}>10{sup 10.5} M{sub ⊙} galaxies, and HIEROs are therefore crucial to understanding the very early phase of massive galaxy formation.

• OSTI ID: 22879401
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 816; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CAMERAS
COLOR
ENERGY SPECTRA
EVOLUTION
GALAXIES
INCLUSIONS
MASS
RED SHIFT
SPACE
STARS
TELESCOPES