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

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 (LSBs; i.e. μ(g,0) <24 mag arcsec⁻²; re comparable to the Galaxy), the red colour (〈g − r〉 ∼ 0.8) and assumed low metallicity of these objects compels us to consider a scenario in which these are underdeveloped galaxies whose early (z ≃ 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 idealized 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 ΛCDM cosmology, classical LSBs, and the role of baryonic physics in their early formation.