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Evolution in the orbital structure of quiescent galaxies from MAGPI, LEGA-C, and SAMI surveys: direct evidence for merger-driven growth over the last 7 Gyr.
- Source :
- Monthly Notices of the Royal Astronomical Society; 10/20/2023, Vol. 525 Issue 2, p2789-2805, 17p
- Publication Year :
- 2023
-
Abstract
- We present the first study of spatially integrated higher-order stellar kinematics over cosmic time. We use deep rest-frame optical spectroscopy of quiescent galaxies at redshifts z  = 0.05, 0.3, and 0.8 from the SAMI, MAGPI, and LEGA-C surveys to measure the excess kurtosis h <subscript>4</subscript> of the stellar velocity distribution, the latter parametrized as a Gauss-Hermite series. Conservatively using a redshift-independent cut in stellar mass (|$M_\star = 10^{11}\, \mathrm{M_\odot }$|) and matching the stellar-mass distributions of our samples, we find 7σ evidence of h <subscript>4</subscript> increasing with cosmic time, from a median value of 0.019 ± 0.002 at z  = 0.8 to 0.059 ± 0.004 at z  = 0.06. Alternatively, we use a physically motivated sample selection based on the mass distribution of the progenitors of local quiescent galaxies as inferred from numerical simulations; in this case, we find 10σ evidence. This evolution suggests that, over the last 7 Gyr, there has been a gradual decrease in the rotation-to-dispersion ratio and an increase in the radial anisotropy of the stellar velocity distribution, qualitatively consistent with accretion of gas-poor satellites. These findings demonstrate that massive galaxies continue to accrete mass and increase their dispersion support after becoming quiescent. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00358711
- Volume :
- 525
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Publication Type :
- Academic Journal
- Accession number :
- 171877283
- Full Text :
- https://doi.org/10.1093/mnras/stad800