Caught in the act: gas and stellar velocity dispersions in a fast Quenching compact star-forming galaxy at z ~ 1.7



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Pérez González, Pablo Guillermo and Cardiel López, Nicolás and Eliche Moral, María del Carmen and otros, ... (2016) Caught in the act: gas and stellar velocity dispersions in a fast Quenching compact star-forming galaxy at z ~ 1.7. Astrophysical journal, 820 (2). ISSN 0004-637X

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We present Keck I MOSFIRE spectroscopy in the Y and H bands of GDN-8231, a massive, compact, star-forming galaxy at a redshift of z ~ 1.7. Its spectrum reveals both Hα and [Nii] emission lines and strong Balmer absorption lines. The Hα and Spitzer MIPS 24 μm fluxes are both weak, thus indicating a low star-formation rate of SFR≲5-10 M_⨀ yr−1. This, added to a relatively young age of ~700 Myr measured from the absorption lines, provides the first direct evidence for a distant galaxy being caught in the act of rapidly shutting down its star formation. Such quenching allows GDN-8231 to become a compact, quiescent galaxy, similar to three other galaxies in our sample, by z ~ 1.5. Moreover, the color profile of GDN-8231 shows a bluer center, consistent with the predictions of recent simulations for an early phase of inside-out quenching. Its line-of-sight velocity dispersion for the gas, σ_LOG^gas = 127 ± 32 km s^−1, is nearly 40% smaller than that of its stars, σ_LOG^* = 215 ± 35 km s^−1. High-resolution hydro-simulations of galaxies explain such apparently colder gas kinematics of up to a factor of ~1.5 with rotating disks being viewed at different inclinations and/or centrally concentrated star-forming regions. A clear prediction is that their compact, quiescent descendants preserve some remnant rotation from their star-forming progenitors.

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© 2016 The American Astronomical Society.
Artículo firmado por 23 autores. 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. and M.C.E.M. acknowledge support from grant AYA2012-31277. J.R.T. acknowledges support from NASA through Hubble Fellowship grant #51330. D.C. acknowledges support from AYA2012-32295. The simulations were performed at NASA Advanced Super-computing (NAS) at NASA Ames Research Center. 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). 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. Based partly on observations made with the Gran Telescopio Canarias (GTC), installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma.

Uncontrolled Keywords:Greater-than 1; Post-starburst galaxies; Hubble-space-telescope; Absorption-line spectroscopy; Passively evolving galaxies; Extragalactic legacy survey; Near-infrared spectroscopy; K-selected galaxies; Inside-out growth; Quiescent galaxies
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:38002
Deposited On:06 Jun 2016 14:38
Last Modified:10 Dec 2018 15:04

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