The stellar-to-halo mass relations of local galaxies segregates by color

TL;DR

This study reveals that the stellar-to-halo mass relation differs between blue and red central galaxies, with blue galaxies having higher ratios and different environmental dependencies, highlighting the role of quenching and environment in galaxy evolution.

Contribution

It provides the first detailed segregation of the stellar-to-halo mass relation by galaxy color for local central galaxies, including the fraction of halos hosting each type.

Findings

Blue centrals have higher Ms/Mh ratios than red centrals.

The SHMR scatter is smaller for blue centrals (~0.11dex) than red centrals (~0.14dex).

The fraction of halos hosting blue centrals decreases with halo mass, from 87% at 10^11 Msun to a few percent at higher masses.

Abstract

We derive the stellar-to-halo mass relations, SHMR, of local blue and red central galaxies separately, as well as the fraction of halos hosting blue/red central galaxies. We find that: 1) the SHMR of central galaxies is segregated by color, with blue centrals having a SHMR above the one of red centrals; at logMh~12, the Ms/Mh ratio of the blue centrals is ~0.05, which is ~1.7 times larger than the value of red centrals. 2) The intrinsic scatters of the SHMRs of red and blue centrals are ~0.14 and ~0.11dex, respectively. The intrinsic scatter of the average SHMR of all central galaxies changes from ~0.20dex to ~0.14dex in the 11.3<logMh<15 range. 3) The fraction of halos hosting blue centrals at Mh=1E11Msun is 87%, but at 2x1E12Msun decays to ~20%, approaching to a few per cents at higher masses. The characteristic mass at which this fraction is the same for blue and red galaxies is Mh~7x1E11Msun. Our results suggest that the SHMR of central galaxies at large masses is shaped by halo mass quenching (likely through shock virial heating and AGN feedback), but group richness also plays an important role: central galaxies living in less dense environments quenched their star formation later or did not quench it yet. At low masses, processes that delay star formation without invoking too strong supernova-driven outflows could explain the high Ms/Mh ratios of blue centrals as compared to those of the scarce red centrals.