Spatially Resolved Stellar Kinematics from LEGA-C: Increased Rotational Support in z ̃ 0.8 Quiescent Galaxies
Journal
Date Issued
2018
Author(s)
Bezanson, Rachel
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Pacifici, Camilla
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Noeske, Kai
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Barišić, Ivana
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Bell, Eric F.
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Brammer, Gabriel B.
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Calhau, Joao
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Chauke, Priscilla
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van Dokkum, Pieter
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Franx, Marijn
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•
van Houdt, Josha
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Labbé, Ivo
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Maseda, Michael V.
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Muños-Mateos, Juan Carlos
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Muzzin, Adam
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van de Sande, Jesse
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Sobral, David
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Straatman, Caroline
•
Wu, Po-Feng
Abstract
We present stellar rotation curves and velocity dispersion profiles for 104 quiescent galaxies at z = 0.6-1 from the Large Early Galaxy Astrophysics Census (LEGA-C) spectroscopic survey. Rotation is typically probed across 10-20 kpc, or to an average of 2.7Re. Combined with central stellar velocity dispersions (σ0) this provides the first determination of the dynamical state of a sample selected by a lack of star formation activity at large lookback time. The most massive galaxies (M⋆ > 2 × 1011 M☉) generally show no or little rotation measured at 5 kpc (| {V}5| /{σ }0< 0.2 in eight of ten cases), while ̃64% of less massive galaxies show significant rotation. This is reminiscent of local fast- and slow-rotating ellipticals and implies that low- and high-redshift quiescent galaxies have qualitatively similar dynamical structures. We compare | {V}5| /{σ }0 distributions at z ̃ 0.8 and the present day by re-binning and smoothing the kinematic maps of 91 low-redshift quiescent galaxies from the Calar Alto Legacy Integral Field Area (CALIFA) survey and find evidence for a decrease in rotational support since z ̃ 1. This result is especially strong when galaxies are compared at fixed velocity dispersion; if velocity dispersion does not evolve for individual galaxies then the rotational velocity at 5 kpc was an average of 94 ± 22% higher in z ̃ 0.8 quiescent galaxies than today. Considering that the number of quiescent galaxies grows with time and that new additions to the population descend from rotationally supported star-forming galaxies, our results imply that quiescent galaxies must lose angular momentum between z ̃ 1 and the present, presumably through dissipationless merging, and/or that the mechanism that transforms star-forming galaxies also reduces their rotational support.
Volume
858
Issue
1
Start page
60
Issn Identifier
0004-637X
Ads BibCode
2018ApJ...858...60B
Rights
open.access
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