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Published November 10, 2014 | Submitted + Published
Journal Article Open

Keck-I MOSFIRE Spectroscopy of Compact Star-forming Galaxies at z ≳ 2: High Velocity Dispersions in Progenitors of Compact Quiescent Galaxies

Abstract

We present Keck-I MOSFIRE near-infrared spectroscopy for a sample of 13 compact star-forming galaxies (SFGs) at redshift 2 ≤ z ≤ 2.5 with star formation rates of SFR ~ 100 M_☉ yr^(–1) and masses of log(M/M_☉) ~10.8. Their high integrated gas velocity dispersions of σ_(int_ =230^(+40)_(-30) km s^(–1), as measured from emission lines of Hα and [O III], and the resultant M_* -σ_(int) relation and M_*-M_(dyn) all match well to those of compact quiescent galaxies at z ~ 2, as measured from stellar absorption lines. Since log(M*/M_(dyn)) =–0.06 ± 0.2 dex, these compact SFGs appear to be dynamically relaxed and evolved, i.e., depleted in gas and dark matter (<13^(+17)_(-13)%), and present larger σ_(int) than their non-compact SFG counterparts at the same epoch. Without infusion of external gas, depletion timescales are short, less than ~300 Myr. This discovery adds another link to our new dynamical chain of evidence that compact SFGs at z ≳ 2 are already losing gas to become the immediate progenitors of compact quiescent galaxies by z ~ 2.

Additional Information

© 2014 American Astronomical Society. Received 2014 May 28; accepted 2014 September 15; published 2014 October 23. We thank Sirio Belli for useful discussions and Dan Masters for providing us with additional data for his galaxies. Support for program number HST-GO-12060 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. G.B. acknowledges support from NSF grant AST-08-08133. P.G.P.-G. acknowledges support from grant AYA2012-31277-E. This work has made use of the Rainbow Cosmological Surveys Database, which is operated by the Universidad Complutense de Madrid (UCM), partnered with the University of California Observatories at Santa Cruz (UCO/ Lick, UCSC). C.P. is supported by the KASI–Yonsei Joint Research Program (2014) for the Frontiers of Astronomy and Space Science funded by the Korea Astronomy and Space Science Institute. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

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Published - 0004-637X_795_2_145.pdf

Submitted - 1405.7042v1.pdf

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August 22, 2023
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