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arXiv · 2512.07952

LEGA-C stellar populations scaling relations. I: Chemo-archaeological downsizing trends at z~0.7

Anna R. Gallazzi·Stefano Zibetti·Arjen van der Wel·Angelos Nersesian·Yasha Kaushal·Rachel Bezanson·Francesco D'Eugenio·Eric F. Bell·Joel Leja·Laura Scholz-Diaz·Po-Feng Wu·Camilla Pacifici·Michael Maseda·Daniele Mattolini
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Abstract

We analyze stellar population properties of 552 galaxies at redshift 0.6 =0.7 and masses >10^10Msun. The downsizing trends observed locally were already in place 6 Gyr ago. We observe bimodal age distribution as a function of mass, transitioning around 10^11Msun. No bimodality appears in the stellar metallicity-mass relation, which changes from steep to flat across 10^10.8Msun. Similar trends emerge for age and metallicity with velocity dispersion, but with sharper transition from young to old around log(sigma)=2.3. Differences with respect to trens with stellar mass suggest that age primarily depends on velocity dispersion below and above the transition regime, while both stellar mass and velocity dispersion contribute to stellar metallicity. The catalogs of revised absorption index measurements for LEGA-C DR3 and inferred stellar population physical parameters will be released to public repositories. (Abridged)

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Anna R. Gallazzi, Stefano Zibetti, Arjen van der Wel, Angelos Nersesian, Yasha Kaushal, Rachel Bezanson, Francesco D'Eugenio, Eric F. Bell, Joel Leja, Laura Scholz-Diaz, Po-Feng Wu, Camilla Pacifici, Michael Maseda, Daniele Mattolini. 2025-12-08. LEGA-C stellar populations scaling relations. I: Chemo-archaeological downsizing trends at z~0.7. https://doi.org/10.1051/0004-6361%2F202554922

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