The dependence of the galaxy stellar-to-halo mass relation on galaxy morphology

TL;DR

This study explores how galaxy morphology influences the stellar-to-halo mass relation using SDSS data and simulations, revealing differences in mass assembly and black hole growth between disc and elliptical galaxies across halo masses.

Contribution

It provides new insights into the dependence of the stellar-to-halo mass relation on galaxy morphology, combining observational data with cosmological simulations.

Findings

Discs are more massive than ellipticals at certain halo masses.

Galaxy assembly history varies with morphology and halo mass.

Black hole growth differs between ellipticals and discs in specific halo ranges.

Abstract

We investigate the dependence of the local galaxy stellar-to-halo mass relation (SHMR) on galaxy morphology. We use data from the Sloan Digital Sky Survey DR7 with morphological classifications from Galaxy Zoo, and compare with the EAGLE cosmological simulation. At fixed halo mass in the mass range $10^{11.7}-10^{12.9}M_{\odot}$, the median stellar masses of SDSS disc galaxies are up to a factor of 1.4 higher than the median masses of their elliptical counterparts. However, when we switch from the stellar masses from Kauffmann et al. to those calculated by Chang et al. or Brinchmann et al., the median SHMR from discs and ellipticals coincide in this mass range. For halo masses larger than $10^{13}M_{\odot}$, discs are less massive than ellipticals in same-mass haloes, regardless of whose stellar mass estimates we use. However, we find that for these high halo masses the results for discs may be affected by central/satellite misclassifications. The EAGLE simulation predicts that discs are up to a factor of 1.5 more massive than elliptical galaxies residing in same-mass haloes less massive than $10^{13}M_{\odot}$, in agreement with the Kauffmann et al. data. Haloes with masses between $10^{11.5}$ and $10^{12}M_{\odot}$, that host disc galaxies, were assembled earlier than those hosting ellipticals. This suggests that the discs are more massive because they had more time for gas accretion and star formation. In $10^{12}-10^{12.5}M_{\odot}$ haloes, the central black holes in elliptical galaxies grew faster and became more massive than their counterparts in disc galaxies. This suggests that in this halo mass range the ellipticals are less massive because AGN feedback ejected more of the halo's gas reservoir, reducing star formation, and suppressing the (re)growth of stellar discs.