The evolution of compact massive quiescent and starforming galaxies derived from the $R_e-R_h$ and $M_{rm star}-M_h$ relations. (arXiv:2105.09969v1 [astro-ph.GA])

The evolution of compact massive quiescent and starforming galaxies derived from the $R_e-R_h$ and $M_{rm star}-M_h$ relations. (arXiv:2105.09969v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Zanisi_L/0/1/0/all/0/1">L. Zanisi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shankar_F/0/1/0/all/0/1">F. Shankar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fu_H/0/1/0/all/0/1">H. Fu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rodriguez_Puebla_A/0/1/0/all/0/1">A. Rodriguez-Puebla</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Avila_Reese_V/0/1/0/all/0/1">V. Avila-Reese</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Faisst_A/0/1/0/all/0/1">A. Faisst</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Daddi_E/0/1/0/all/0/1">E. Daddi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Boco_L/0/1/0/all/0/1">L. Boco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lapi_A/0/1/0/all/0/1">A. Lapi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Giavalisco_M/0/1/0/all/0/1">M. Giavalisco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saracco_P/0/1/0/all/0/1">P. Saracco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Buitrago_F/0/1/0/all/0/1">F. Buitrago</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huertas_Company_M/0/1/0/all/0/1">M. Huertas-Company</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Puglisi_A/0/1/0/all/0/1">A. Puglisi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dekel_A/0/1/0/all/0/1">A. Dekel</a>

The mean size ( effective radius $R_e$) of Massive Galaxies (MGs, $M_{rm
star}>10^{11.2}M_odot$) 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 $sigma_{rm SMHM}$ in stellar mass at fixed halo mass, and assign
sizes to galaxies using an empirically-motivated, constant and linear
relationship between $R_e$ and the host dark matter halo radius $R_h$. 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 $zgtrsim2$ and fall off at lower redshifts, suggesting a lesser
role of progenitor bias at later epochs; 3) a time-independent scatter
$sigma_{rm SMHM}$ is consistent with a scenario in which compact starforming
MGs transition into quiescent MGs in a few $10^8$yr with a negligible
structural evolution during the compact phase, while a scatter increasing at
high redshift implies significant size growth during the starforming 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.

The mean size ( effective radius $R_e$) of Massive Galaxies (MGs, $M_{rm
star}>10^{11.2}M_odot$) 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 $sigma_{rm SMHM}$ in stellar mass at fixed halo mass, and assign
sizes to galaxies using an empirically-motivated, constant and linear
relationship between $R_e$ and the host dark matter halo radius $R_h$. 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 $zgtrsim2$ and fall off at lower redshifts, suggesting a lesser
role of progenitor bias at later epochs; 3) a time-independent scatter
$sigma_{rm SMHM}$ is consistent with a scenario in which compact starforming
MGs transition into quiescent MGs in a few $10^8$yr with a negligible
structural evolution during the compact phase, while a scatter increasing at
high redshift implies significant size growth during the starforming 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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