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Title: An Hi-absorption-selected Cold Rotating Disk Galaxy at z ≈ 2.193
Abstract We have used the Atacama Large Millimeter/submillimeter Array to map CO(3–2) emission from a galaxy, DLA-B1228g, associated with the high-metallicity damped Lyαabsorber atz≈ 2.1929 toward the QSO PKS B1228–113. At an angular resolution of ≈0.″32 × 0.″24, DLA-B1228g shows extended CO(3–2) emission with a deconvolved size of ≈0.″78 × 0.″18, i.e., a spatial extent of ≈6.4 kpc. We detect extended stellar emission from DLA-B1228g in a Hubble Space Telescope Wide Field Camera 3 F160W image and find that Hαemission is detected in a Very Large Telescope SINFONI image from only one side of the galaxy. While the clumpy nature of the F160W emission and the offset between the kinematic and physical centers of the CO(3–2) emission are consistent with a merger scenario, this appears unlikely due to the lack of strong Hαemission, the symmetric double-peaked CO(3–2) line profile, the high molecular gas depletion timescale, and the similar velocity dispersions in the two halves of the CO(3–2) image. Kinematic modeling reveals that the CO(3–2) emission is consistent with arising from an axisymmetric rotating disk with an exponential profile, a rotation velocity ofvrot= 328 ± 7 km s−1, and a velocity dispersion ofσv= 62 ± 7 km s−1. The high value of the ratiovrot/σv, ≈5.3, implies that DLA-B1228g is a rotation-dominated cold disk galaxy, the second case of a high-zHi-absorption-selected galaxy identified with a cold rotating disk. We obtain a dynamical mass ofMdyn= (1.5 ± 0.1) × 1011M⊙, similar to the molecular gas mass of ≈1011M⊙inferred from earlier CO(1–0) studies; this implies that the galaxy is baryon-dominated in its inner regions.  more » « less
Award ID(s):
2107989 2534994
PAR ID:
10533205
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal Letters
Volume:
971
Issue:
2
ISSN:
2041-8205
Format(s):
Medium: X Size: Article No. L33
Size(s):
Article No. L33
Sponsoring Org:
National Science Foundation
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