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Title: Molecular Gas Excitation of the Massive Dusty Starburst CRLE and the Main-sequence Galaxy HZ10 at z = 5.7 in the COSMOS Field
Abstract

We report CO(5 → 4) and CO(6 → 5) line observations in the dusty starbursting galaxy CRLE (z= 5.667) and the main-sequence (MS) galaxy HZ10 (z= 5.654) with the Northern Extended Millimeter Array. CRLE is the most luminousz> 5 starburst in the COSMOS field and HZ10 is the most gas-rich “normal” galaxy currently known atz> 5. We find line luminosities for CO(5 → 4) and CO(6 → 5) of (4.9 ± 0.5) and (3.8 ± 0.4) × 1010K km s−1pc2for CRLE and upper limits of < 0.76 and < 0.60 × 1010K km s−1pc2for HZ10, respectively. The CO excitation of CRLE appears comparable to otherz> 5 dusty star-forming galaxies. For HZ10, these line luminosity limits provide the first significant constraints of this kind for an MS galaxy atz> 5. We find the upper limit ofL54/L21in HZ10 could be similar to the average value for MS galaxies aroundz≈ 1.5, suggesting that MS galaxies with comparable gas excitation may already have existed one billion years after the Big Bang. For CRLE we determine the most likely values for the H2density, kinetic temperature, and dust temperature based on excitation modeling of the CO line ladder. We also derive a total gas mass of (7.1 ± 1.3) × 1010M. Our findings provide some of the currently most detailed constraints on the gas excitation that sets the conditions for star formation in a galaxy protocluster environment atz> 5.

 
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Award ID(s):
1910107 1716229
NSF-PAR ID:
10362246
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
925
Issue:
2
ISSN:
0004-637X
Format(s):
Medium: X Size: Article No. 174
Size(s):
["Article No. 174"]
Sponsoring Org:
National Science Foundation
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