Galaxy Populations in Groups and Clusters: II. Conditional Luminosity Functions at Redshifts from z ~ 1 to z ~ 0

TL;DR

This study measures the evolution of galaxy luminosity functions in groups and clusters from redshift 1 to 0, revealing weak satellite evolution and persistent red faint-end upturns, informing galaxy formation theories.

Contribution

First measurement of CLFs for red and blue galaxies in halos from 10^{12} to 10^{15} solar masses across z=0 to 1, with unprecedented faint limits and detailed evolutionary insights.

Findings

Blue satellite CLFs are well described by a single Schechter function with nearly constant slope.

Red satellite CLFs show a faint-end upturn with little evolution in slope.

Red centrals evolve passively, blue centrals' luminosity driven by star formation.

Abstract

Using DESI SV3 spectroscopic group centrals together with deep HSC photometric data, we measure the conditional luminosity functions (CLFs) of central and satellite galaxies, separately for red and blue populations, in dark matter halos spanning $M_h\sim10^{12}- 10^{15}M_{\odot}$ and $0<z<1$. The depth of the HSC imaging enables CLFs to be measured to unprecedentedly faint limits, reaching $M_r \approx -15$ at $0.2 \leqslant z < 0.5$ and $M_r \approx -17$ at $0.5 \leqslant z < 1.0$. We find a remarkably weak evolution in the CLF of satellite galaxies over $0<z<1$. The Blue satellite CLFs are well described by a single Schechter function across all halo masses and redshifts, with a nearly constant slope of $-1.25\lesssim \alpha\lesssim -1.2$. In contrast, red satellite CLFs exhibit a pronounced and ubiquitous faint-end upturn in all halo mass and redshift bins, with little evolution in the faint-end slope ($-1.8\lesssim \alpha_f\lesssim -1.7$). These results indicate that the low-mass end of the red sequence in clusters/groups was already established by $z\sim1$. Both satellite characteristic magnitudes and central galaxy luminosities fade with time. Red central galaxies are consistent with passive evolution, whereas the luminosity evolution of blue centrals is dominated by ongoing star formation. Satellite galaxies evolve more rapidly than predicted by simple stellar population models, highlighting the importance of environmental effects. The quenched fraction of satellite galaxies as a function of stellar mass exhibits a universal minimum at $M_{\ast} \sim 10^9M_{\odot}$, independent of halo mass and redshift. We discuss possible interpretations of these results and their implications for galaxy formation and evolution.