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 Gy ...

• Main Authors: D'Eugenio, Francesco, van der Wel, Arjen, Piotrowska, Joanna M., Bezanson, Rachel, Taylor, Edward N., van de Sande, Jesse, Baker, William M., Bell, Eric F., Bellstedt, Sabine, Bland-Hawthorn, Joss, Bluck, Asa F. L., Brough, Sarah, Bryant, Julia J., Colless, Matthew, Cortese, Luca, Croom, Scott M., Derkenne, Caro, van Dokkum, Pieter, Fisher, Deanne, Foster, Caroline, Gallazzi, Anna, de Graaff, Anna, Groves, Brent, van Houdt, Josha, Lagos, Claudia del P., Looser, Tobias J., Maiolino, Roberto, Maseda, Michael, Mendel, J. Trevor, Nersesian, Angelos, Pacifici, Camilla, Poci, Adriano, Remus, Rhea-Silvia, Sweet, Sarah M., Thater, Sabine, Tran, Kim-Vy, Übler, Hannah, Valenzuela, Lucas M., Wisnioski, Emily, Zibetti, Stefano
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: arXiv 2023
• Subjects: Astrophysics of Galaxies astro-ph.GA; FOS Physical sciences; sami
• Online Access: https://dx.doi.org/10.48550/arxiv.2303.05520; https://arxiv.org/abs/2303.05520

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 $h_4$ of the stellar velocity distribution, the latter parametrised as a Gauss-Hermite series. Conservatively using a redshift-independent cut in stellar mass ($M_\star = 10^{11}\,{\rm M}_\odot$), and matching the stellar-mass distributions of our samples, we find 7 $σ$ evidence of $h_4$ increasing with cosmic time, from a median value of 0.019$\pm$0.002 at z=0.8 to 0.059$\pm$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 10 $σ$ 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 ... : 19 pages, 9 figures Accepted for publication in MNRAS ...