# Investigating the Stellar Mass Growth Histories of Satellite Galaxies as a Function of Infall Time using Phase-Space

## TL;DR

This study examines how satellite galaxies' stellar mass growth histories depend on infall time, revealing early quenching signs and the influence of host mass, including low-mass groups, with evidence of pre-processing before cluster entry.

## Contribution

It introduces a method to classify satellites by infall time using phase-space and compares their mass growth histories, highlighting the impact of host environment and pre-processing effects.

## Key findings

- Ancient infallers show earlier quenching, especially in massive hosts.
- Low-mass groups can significantly affect satellite evolution.
- Pre-processing occurs in protocluster outskirts before infall.

## Abstract

We compile a large sample of nearby galaxies that are satellites of hosts using a well known SDSS group catalogue. From this sample, we create an `ancient infallers' and `recent infallers' subsample, based on the mean infall time predicted from cosmological simulations for galaxies with their location in phase-space. We compare the stellar mass growth histories of the galaxies in these two subsamples, as determined from multi-wavelength SED fitting that uses a comprehensive library of star formation history shapes derived from cosmological simulations. By simultaneously controlling for satellite stellar mass and host halo mass, we can clearly see the impact of time spent in their hosts. As we might predict, the ancient infaller population shows clear signs of earlier quenching, especially for lower mass satellites in more massive hosts. More importantly, we find the effects are not limited to massive hosts. We find that hosts which might be considered low mass groups (halo masses $\sim$10$^{13}$ M$_\odot$) can significantly alter their satellites, even for massive satellites (stellar masses $\sim$10$^{10}$ M$_\odot$). Intriguingly, we see changes in the mass growth history of the satellites of clusters as early as 8 or 9 Gyr ago, when they had not yet entered the virial radius of their current host. We propose that this could be the result of galaxies being pre-processed in low-mass substructures in the protocluster outskirts, prior to infall.