2023ApJ...952...48H -
Astrophys. J., 952, 48 (2023/July-3)
Big Three Dragons: Molecular Gas in a Bright Lyman-break Galaxy at z = 7.15.
HASHIMOTO T., INOUE A.K., SUGAHARA Y., FUDAMOTO Y., FUJIMOTO S., KNUDSEN K.K., MATSUO H., TAMURA Y., YAMANAKA S., HARIKANE Y., KUNO N., ONO Y., SALAK D. and ISHII N.
Abstract (from CDS):
We report Atacama Large Millimeter/submillimeter Array Band 3 observations of CO(6-5), CO(7-6), and [C I](2-1) in B14-65666 (“Big Three Dragons”), one of the brightest Lyman-break galaxies at z > 7 in the rest-frame ultraviolet continuum, far-infrared continuum, and emission lines of [O III] 88 μm and [C II] 158 μm. CO(6-5), CO(7-6), and [C I](2-1), whose 3σ upper limits on the luminosities are approximately 40 times fainter than the [C II] luminosity, are all not detected. The L_[C II]_/LCO(6–5) and L_[C II]_/LCO(7–6) ratios are higher than the typical ratios obtained in dusty star-forming galaxies or quasar host galaxies at similar redshifts, and they may suggest a lower gas density in the photodissociated region in B14-65666. By using the (1) [C II] luminosity, (2) dust mass-to-gas mass ratio, and (3) a dynamical mass estimate, we find that the molecular gas mass (Mmol) is (0.05-11) × 1010M⊙. This value is consistent with the upper limit inferred from the nondetection of mid-J CO and [C I](2-1). Despite the large uncertainty in Mmol, we estimate a molecular gas-to-stellar mass ratio (μgas) of 0.65-140 and a gas depletion time (τdep) of 2.5-550 Myr; these values are broadly consistent with those of other high-redshift galaxies. B14-65666 could be an ancestor of a passive galaxy at z ≳ 4 if no gas is fueled from outside the galaxy.
Abstract Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
High-redshift galaxies - Galaxies - Interstellar medium
Simbad objects:
5
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