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20 April 2024 |
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Caught in the act: gas and stellar velocity dispersions in a fast quenching compact star-forming galaxy at z~1.7 | | G. Barro
; S. M. Faber
; A. Dekel
; C. Pacifici
; P. G. Perez-Gonzalez
; E. Toloba
; D. C. Koo
; J. R. Trump
; S. Inoue
; Y. Guo
; F. Liu
; J. R. Primack
; A. M. Koekemoer
; G. Brammer
; A. Cava
; N. Cardiel
; D. Ceverino
; C. M. Eliche
; J. J. Fang
; S. L. Finkelstein
; D. D. Kocevski
; R. C. Livermore
; E. McGrath
; | | Date: |
24 Mar 2015 | | Abstract: | We present Keck-I MOSFIRE spectroscopy in the Y and H bands of GDN-8231, a
massive, compact, star-forming galaxy (SFG) at a redshift $zsim1.7$. Its
spectrum reveals both H$_{alpha}$ and [NII] emission lines and strong Balmer
absorption lines. The H$_{alpha}$ and Spitzer MIPS 24 $mu$m fluxes are both
weak, thus indicating a low star formation rate of SFR $lesssim5-10$
M$_{odot}$ yr$^{-1}$. This, added to a relatively young age of $sim700$ 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 3 other galaxies in our sample, by $zsim1.5$. 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, $sigma^{
m{gas}}_{!_{
m
LOS}}=127pm32$ km s$^{-1}$, is nearly 40% smaller than that of its stars,
$sigma^{star}_{!_{
m LOS}}=215pm35$ km s$^{-1}$. High-resolution
hydro-simulations of galaxies explain such apparently colder gas kinematics of
up to a factor of $sim1.5$ 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. | | Source: | arXiv, 1503.7164 | | Services: | Forum | Review | PDF | Favorites | |
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