Spatially resolved stellar kinematics from LEGA-C : increased rotational support in z ∼ 0.8 quiescent galaxies

• Published in: The Astrophysical Journal
• Main Authors: Bezanson, Rachel, van der Wel, Arjen, Pacifici, Camilla, Noeske, Kai, Barišić, Ivana, Bell, Eric F, Brammer, Gabriel B, Calhau, Joao, Chauke, Priscilla, van Dokkum, Pieter, Franx, Marijn, Gallazzi, Anna, van Houdt, Josha, Labbé, Ivo, Maseda, Michael V, Muños-Mateos, Juan Carlos, Muzzin, Adam, van de Sande, Jesse, Sobral, David, Straatman, Caroline, Wu, Po-Feng
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: Physics and Astronomy; galaxies; elliptical and lenticular; cD - galaxies; evolution - galaxies; high-redshift - galaxies; kinematics and dynamics - galaxies; structure; HUBBLE-SPACE-TELESCOPE; TULLY-FISHER RELATION; SUPERDENSE MASSIVE GALAXIES; STAR-FORMING GALAXIES; INSIDE-OUT GROWTH; INFRARED SPECTROSCOPIC SURVEY; HIGH-REDSHIFT GALAXIES; K-SELECTED GALAXIES; SAMI PILOT SURVEY; ELLIPTIC GALAXIES; Hubble; sami
• 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

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.