An ALMA Multiline Survey of the Interstellar Medium of the Redshift 7.5 Quasar Host Galaxy J1342+0928
Journal
Date Issued
2019
Author(s)
Novak, Mladen
•
Bañados, Eduardo
•
•
Walter, Fabian
•
Venemans, Bram
•
Neeleman, Marcel
•
Farina, Emanuele Paolo
•
Mazzucchelli, Chiara
•
Carilli, Chris
•
Fan, Xiaohui
•
Rix, Hans─Walter
•
Wang, Feige
Abstract
We use Atacama Large Millimeter Array observations of the host galaxy of the quasar ULAS J1342+0928 at z = 7.54, to study the dust continuum and far-infrared lines emitted from its interstellar medium (ISM). The Rayleigh-Jeans tail of the dust continuum is well sampled with eight different spectral setups, and from a modified blackbody fit we obtain an emissivity coefficient of β = 1.85 ± 0.3. Assuming a standard dust temperature of 47 K we derive a dust mass of M dust = 0.35 × 108 M ☉ and a star formation rate of 150+/- 30 {M}☉ {yr}}-1. We have >4σ detections of the {[{{C}}{{II}}]}158μ {{m}}, {[{{O}}{{III}}]}88μ {{m}}, and {[{{N}}{{II}}]}205μ {{m}} atomic fine structure lines and limits on the {[{{C}}{{I}}]}369μ {{m}}, {[{{O}}{{I}}]}146μ {{m}}, and {[{{N}}{{II}}]}205μ {{m}} emission. We also report multiple limits of CO rotational lines with J up ≥ 7, as well as a tentative 3.3σ detection of the stack of four CO lines (J up = 11, 10, 8, and 7). We find line deficits that are in agreement with local ultra-luminous infrared galaxies. Comparison of the {[{{N}}{{II}}]}205μ {{m}} and {[{{C}}{{II}}]}158μ {{m}} lines indicates that the {[{{C}}{{II}}]}158μ {{m}} emission arises predominantly from the neutral medium, and we estimate that the photodisassociation regions in J1342+0928 have densities ≲5 × 104 cm-3. The data suggest that ∼16% of hydrogen is in ionized form and that the H II regions have high electron densities of n e > 180 cm-3. Our observations favor a low gas-to-dust ratio of <100, and a metallicity of the ISM comparable to the solar value. All the measurements presented here suggest that the host galaxy of J1342+0928 is highly enriched in metal and dust, despite being observed just 680 Myr after the big bang.
Volume
881
Issue
1
Start page
63
Issn Identifier
0004-637X
Ads BibCode
2019ApJ...881...63N
Rights
open.access
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