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arXiv · 1812.06095

The ISM Properties and Gas Kinematics of a Redshift 3 Massive Dusty Star-forming Galaxy

T. K. Daisy Leung·Dominik A. Riechers·Andrew J. Baker·Dave L. Clements·Asantha Cooray·Christopher C. Hayward·R. J. Ivison·Roberto Neri·Alain Omont·Ismael Perez-Fournon·Douglas Scott·Julie L. Wardlow
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Abstract

We present CO(J= 1-0; 3-2; 5-4; 10-9) and 1.2-kpc resolution [CII] line observations of the dusty star-forming galaxy (SFG) HXMM05 -- carried out with the Karl G. Jansky Very Large Array, the Combined Array for Research in Millimeter-wave Astronomy, the Plateau de Bure Interferometer, and the Atacama Large Millimeter/submillimeter Array, measuring an unambiguous redshift of z = 2.9850+/-0.0009. We find that HXMM05 is a hyper-luminous infrared galaxy (LIR=(4+/-1)x10^13 Lsun) with a total molecular gas mass of (2.1+/-0.7)x10^11 (alpha_CO/0.8) Msun. The CO(J=1-0) and [CII] emission are extended over ~9 kpc in diameter, and the CO line FWHM exceeds 1100 km s^-1. The [CII] emission shows a monotonic velocity gradient consistent with a disk, with a maximum rotation velocity of v_c = 616+/-100 km s^-1 and a dynamical mass of (7.7+/-3.1)x10^11 Msun. We find a star formation rate (SFR) of 2900^750_-595 Msun yr^-1. HXMM05 is thus among the most intensely star-forming galaxies known at high redshift. Photo-dissociation region modeling suggests physical conditions similar to nearby SFGs, showing extended star formation, which is consistent with our finding that the gas and dust emission are co-spatial. Its molecular gas excitation resembles the local major merger Arp 220. The broad CO and [CII] lines and a pair of compact dust nuclei suggest the presence of a late-stage major merger at the center of the extended disk, again reminiscent of Arp 220. The observed gas kinematics and conditions together with the presence of a companion and the pair of nuclei suggest that HXMM05 is experiencing multiple mergers as a part of the evolution.

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T. K. Daisy Leung, Dominik A. Riechers, Andrew J. Baker, Dave L. Clements, Asantha Cooray, Christopher C. Hayward, R. J. Ivison, Roberto Neri, Alain Omont, Ismael Perez-Fournon, Douglas Scott, Julie L. Wardlow. 2018-12-14. The ISM Properties and Gas Kinematics of a Redshift 3 Massive Dusty Star-forming Galaxy. https://doi.org/10.3847/1538-4357%2Faaf860

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