The quenching and survival of ultra-diffuse galaxies in the Coma cluster

TL;DR

This study uses self-consistent simulations to explore the origin and survival of ultra-diffuse galaxies in the Coma cluster, suggesting they are underdeveloped galaxies quenched early by environmental effects.

Contribution

First simulation-based analysis of ultra-diffuse galaxies in Coma, linking their properties to early formation and environmental quenching within a ΛCDM framework.

Findings

Simulations support early quenching as a formation scenario.

Ultra-diffuse galaxies are consistent with low surface brightness and large sizes.

These galaxies are a significant population in the Coma cluster.

Abstract

We conduct the first self-consistent numerical simulations of a recently discovered population of 47 large, faint (ultra-diffuse) galaxies, speculated to lie in the Coma cluster. With structural properties consistent with very large low surface brightness systems (i.e. $\mu$(g,0)$<24$ mag arcsec$^{\rm -2}$, r$_{\rm eff}$ comparable to the Galaxy), the red colour ($\langle$g-r$\rangle$$\sim$0.8) and assumed low metallicity of these objects compels us to consider a scenario in which these are underdeveloped galaxies whose early ($z$$\simeq$2) accretion to an overdense environment quenched further growth. Our simulations demonstrate the efficacy of this scenario, with respect to available observational constraints, using progenitor galaxy models derived from scaling relations, and idealised tidal/hydrodynamical models of the Coma cluster. The apparent ubiquity of these objects in Coma implies they constitute an important galaxy population, we accordingly discuss their properties with respect to a $\Lambda$CDM cosmology, classical LSBs, and the role of baryonic physics in their early formation.