Abstract
ABSTRACT We study the population of galaxies around galaxy clusters in the hydrodynamic simulation suite IllustrisTNG 300-1 to study the signatures of their evolutionary history on observable properties. We measure the radial number density profile, phase space distribution, and splashback radius for galaxies of different masses and colours over the redshift range z = 0−1. The three primary physical effects which shape the galaxy distribution within clusters are the galaxy quenching, angular momentum distribution, and dynamical friction. We find three distinct populations of galaxies by applying a Gaussian mixture model to their distribution in colour and mass. They have distinct evolutionary histories and leave distinct signatures on their distribution around cluster haloes. We find that low-mass red galaxies show the most concentrated distribution in clusters and the largest splashback radius, while high-mass red galaxies show a less concentrated distribution and a smaller splashback radius. Blue galaxies, which mostly quench into the low-mass red population, have the shallowest distribution within the clusters, with those on radial orbits quenched rapidly before reaching pericentre. Comparison with the distribution of galaxies from the Dark Energy Survey survey around Sunyaev–Zeldovich clusters from the Atacama Cosmology Telescope and South Pole Telescope surveys shows evidence for differences in galaxy evolution between simulations and data.
Highlights
Galaxies evolve within the potential wells of massive dark matter halos, some of the largest of these bound structures are known as galaxy clusters
Our cluster sample consists of halos with M200m > 5 × 1013h−1M. Note that this is smaller than the mass threshold of clusters typically used in the splashback analysis of observational data; we use this threshold to give us good statistics in the IllustrisTNG-300 box which has a significantly smaller volume than galaxy surveys like the Dark Energy Survey(DES) (Abbott et al 2005) and The Hyper Suprime Cam (HSC) survey (Aihara et al 2018), and fewer massive clusters above the mass threshold used in data
We have studied the evolution of galaxies in galaxy clusters in the IllustrisTNG 300-1 simulation and connected them to observable signatures in their number density profiles, phase space distributions, and splashback radius
Summary
Galaxies evolve within the potential wells of massive dark matter halos, some of the largest of these bound structures are known as galaxy clusters These are relatively easy to observe and characterize and provide an excellent laboratory to test the predictions of hierarchical structure formation and galaxy evolution. In this paper we investigate the connection between galaxy evolution and the colors of observed galaxies and study how different evolutionary histories leave their imprint on the phase space distributions and the shape of the full radial profile of a population of galaxies. We complement and expand upon the results from Shin et al (2019) and Adhikari et al (2020) who have examined the galaxy color and splashback connection by forward modelling observations from cold dark matter (CDM) N-body simulations.
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