Infrared Color Selection of Massive Galaxies at z > 3
Journal
Date Issued
2016
Author(s)
Wang, T.
•
Elbaz, D.
•
Schreiber, C.
•
•
Shu, X.
•
Willner, S. P.
•
Ashby, M. L. N.
•
Huang, J. -S.
•
•
Dekel, A.
•
Daddi, E.
•
Ferguson, H. C.
•
Dunlop, J.
•
Ciesla, L.
•
Koekemoer, A. M.
•
Giavalisco, M.
•
Boutsia, K.
•
Finkelstein, S.
•
Juneau, S.
•
Barro, G.
•
Koo, D. C.
•
Michałowski, M. J.
•
Orellana, G.
•
Lu, Y.
•
•
Bourne, N.
•
Buitrago, F.
•
•
Faber, S. M.
•
Hathi, N.
•
Lucas, R. A.
•
Pérez-González, P. G.
Abstract
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 H160 (H) and Infrared Array Camera (IRAC) 4.5 μm bands, specifically H-[4.5]\gt 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\gt 3 ({JH}-{blue}) and extremely dusty galaxies at z≲ 3 ({JH}-{red}). The 350 arcmin2 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]\lt 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\gt 3) HIEROs, which have a median photometric redshift < z> ∼ 4.4 and stellar mass {M}*∼ {10}10.6 {M}☉ 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}☉ yr-1, leading to a specific SFR, {{sSFR}}\equiv {{SFR}}/{M}*∼ 4.2 Gyr-1, suggesting that the sSFRs for massive galaxies continue to grow at z\gt 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}*≳ {10}11.2 {M}☉ ) compact QS galaxies at z∼ 3 and have the right number density. HIEROs make up ∼ 60% of all galaxies with {M}*\gt {10}10.5 {M}☉ identified at z\gt 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}*\gt {10}10.5 {M}☉ galaxies, and HIEROs are therefore crucial to understanding the very early phase of massive galaxy formation.
Volume
816
Issue
2
Start page
84
Issn Identifier
0004-637X
Ads BibCode
2016ApJ...816...84W
Rights
open.access
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