Spatially resolved stellar kinematics from LEGA-C : increased rotational support in z ∼ 0.8 quiescent galaxies
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 2.7R(e). Combined with central stellar velocit...
Published in: | The Astrophysical Journal |
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Main Authors: | , , , , , , , , , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2018
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Subjects: | |
Online Access: | https://biblio.ugent.be/publication/8562684 http://hdl.handle.net/1854/LU-8562684 https://doi.org/10.3847/1538-4357/aabc55 https://biblio.ugent.be/publication/8562684/file/8580333 |
Summary: | 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 2.7R(e). Combined with central stellar velocity dispersions (sigma(0)) 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-star > 2 x 10(11) M-circle dot) generally show no or little rotation measured at 5 kpc (vertical bar V-5 vertical bar /sigma(0) < 0.2 in eight of ten cases), while similar to 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 vertical bar V-5 vertical bar sigma(0) distributions at z similar to 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 similar to 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 similar to 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 similar to 1 and the present, presumably through dissipationless merging, and/or that the mechanism that transforms star-forming galaxies also reduces their rotational support. |
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