TY - JOUR
T1 - Spectral Energy Distributions of Companion Galaxies to z ∼ 6 Quasars
AU - Mazzucchelli, C.
AU - Decarli, R.
AU - Farina, E. P.
AU - Bañados, E.
AU - Venemans, B. P.
AU - Strauss, M. A.
AU - Walter, F.
AU - Neeleman, M.
AU - Bertoldi, F.
AU - Fan, X.
AU - Riechers, D.
AU - Rix, H. W.
AU - Wang, R.
N1 - Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved..
PY - 2019/8/20
Y1 - 2019/8/20
N2 - 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 o yr-1, and a stellar content of M ∗ < 1010 M o 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 o yr-1 and M ∗ ∼ 9 × 109 M o. 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.
AB - 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 o yr-1, and a stellar content of M ∗ < 1010 M o 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 o yr-1 and M ∗ ∼ 9 × 109 M o. 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.
KW - cosmology: observations
KW - early universe
KW - galaxies: high-redshift
KW - quasars: general
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U2 - 10.3847/1538-4357/ab2f75
DO - 10.3847/1538-4357/ab2f75
M3 - Article
AN - SCOPUS:85072345609
SN - 0004-637X
VL - 881
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 163
ER -