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

Francesco D'Eugenio, Arjen Van Der Wel, Joanna M. Piotrowska, Rachel Bezanson, Edward N. Taylor, Jesse Van De Sande, William M. Baker, Eric F. Bell, Sabine Bellstedt, Joss Bland-Hawthorn, Asa F.L. Bluck, Sarah Brough, Julia J. Bryant, Matthew Colless, Luca Cortese, Scott M. Croom, Caro Derkenne, Pieter Van Dokkum, Deanne Fisher, Caroline FosterAnna Gallazzi, Anna De Graaff, Brent Groves, Josha Van Houdt, Claudia Del P. Lagos, Tobias J. Looser, Roberto Maiolino, Michael Maseda, J. Trevor Mendel, Angelos Nersesian, Camilla Pacifici, Adriano Poci, Rhea Silvia Remus, Sarah M. Sweet, Sabine Thater, Kim Vy Tran, Hannah Übler, Lucas M. Valenzuela, Emily Wisnioski, Stefano Zibetti

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

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 h4 of the stellar velocity distribution, the latter parametrized as a Gauss-Hermite series. Conservatively using a redshift-independent cut in stellar mass () and matching the stellar-mass distributions of our samples, we find 7σ evidence of h4 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.

Original languageEnglish
Pages (from-to)2789-2805
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Volume525
Issue number2
DOIs
Publication statusPublished - 1 Oct 2023

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