Spectral Energy Distributions of Companion Galaxies to z ∼ 6 Quasars

Journal
Date Issued
2019
Author(s)
Mazzucchelli, C.
•
•
Farina, E. P.
•
Bañados, E.
•
Venemans, B. P.
•
Strauss, M. A.
•
Walter, F.
•
Neeleman, M.
•
Bertoldi, F.
•
Fan, X.
•
Riechers, D.
•
Rix, H. -W.
•
Wang, R.
DOI
Abstract
Massive, quiescent galaxies are already observed at redshift z ∼ 4, i.e., ∼1.5 Gyr after the big bang. Current models predict them to be formed via massive, gas-rich mergers at z > 6. Recent ALMA observations of the cool gas and dust in z ≳ 6 quasars have discovered [C II]- and far-infrared-bright galaxies adjacent to several quasars. In this work, we present sensitive imaging and spectroscopic follow-up observations, with HST/WFC3, Spitzer/IRAC, VLT/MUSE, Magellan/FIRE, and LBT/LUCI-MODS, of ALMA-detected, dust-rich companion galaxies of four quasars at z ≳ 6, specifically acquired to probe their stellar content and unobscured star formation rate. Three companion galaxies do not show significant emission in the observed optical/IR wavelength range. The photometric limits suggest that these galaxies are highly dust-enshrouded, with unobscured star formation rates SFRUV < few M ☉ yr-1, and a stellar content of M * < 1010 M ☉ yr-1. However, the companion to PJ167-13 shows bright rest-frame UV emission (F140W AB = 25.48). Its spectral energy distribution resembles that of a star-forming galaxy with a total SFR ∼ 50 M ☉ yr-1 and M * ∼ 9 × 109 M ☉. All the companion sources are consistent with residing on the galaxy main sequence at z ∼ 6. Additional, deeper data from future facilities, such as the James Webb Space Telescope, are needed in order to characterize these gas-rich sources in the first gigayear of cosmic history.
Volume
881
Issue
2
Start page
163
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2019ApJ...881..163M
Rights
open.access
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