The evolution of compact massive quiescent and star-forming galaxies derived from the R<SUB>e</SUB>-R<SUB>h</SUB> and M<SUB>star</SUB>-M<SUB>h</SUB> relations

Zanisi, L.; Shankar, F.; Fu, H.; Rodriguez-Puebla, A.; Avila-Reese, V.; Faisst, A.; Daddi, E.; Boco, L.; Lapi, A.; Giavalisco, M.; Saracco, P.; Buitrago, F.; Huertas-Company, M.; Puglisi, A.; Dekel, A.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society

Advertised on:
8
2021
Number of authors
15
IAC number of authors
1
Citations
14
Refereed citations
13
Description
The mean size (effective radius Re) of massive galaxies (MGs; Mstar > 1011.2M⊙) is observed to increase steadily with cosmic time. It is still unclear whether this trend originates from the size growth of individual galaxies (via, e.g. mergers and/or AGN feedback) or from the inclusion of larger galaxies entering the selection at later epochs (progenitor bias). We here build a data-driven, flexible theoretical framework to probe the structural evolution of MGs. We assign galaxies to dark matter haloes via stellar mass-halo mass (SMHM) relations with varying high-mass slopes and scatters σSMHM in stellar mass at fixed halo mass, and assign sizes to galaxies using an empirically motivated, constant and linear relationship between Re and the host dark matter halo radius Rh. We find that (1) the fast mean size growth of MGs is well reproduced independently of the shape of the input SMHM relation; (2) the numbers of compact MGs grow steadily until z ≳ 2 and fall off at lower redshifts, suggesting a lesser role of progenitor bias at later epochs; (3) a time-independent scatter σSMHM is consistent with a scenario in which compact star-forming MGs transition into quiescent MGs in a few 108 yr with a negligible structural evolution during the compact phase, while a scatter increasing at high redshift implies significant size growth during the star-forming phase. A robust measurement of the size function of MGs at high redshift can set strong constraints on the scatter of the SMHM relation and, by extension, on models of galaxy evolution.
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Traces of Galaxy Formation: Stellar populations, Dynamics and Morphology
We are a large, diverse, and very active research group aiming to provide a comprehensive picture for the formation of galaxies in the Universe. Rooted in detailed stellar population analysis, we are constantly exploring and developing new tools and ideas to understand how galaxies came to be what we now observe.
Ignacio
Martín Navarro