Exploring the effect of baryons on the radial distribution of satellite galaxies with GAMA and IllustrisTNG

Abstract

We explore the radial distribution of satellite galaxies in groups in the Galaxy and Mass Assembly (GAMA) survey and the IllustrisTNG simulations. Considering groups with masses $12.0 \le \log _{10} (\mathcal {M}_h / h^{-1} \, \mathrm{M}_{\odot }) < 14.8$ at z < 0.267, we find a good agreement between GAMA and a sample of TNG300 groups and galaxies designed to match the GAMA selection. Both display a flat profile in the centre of groups, followed by a decline that becomes steeper towards the group edge, and normalised profiles show no dependence on group mass. Using matched satellites from TNG and dark matter-only TNG-Dark runs we investigate the effect of baryons on satellite radial location. At z = 0, we find that the matched subhaloes from the TNG-Dark runs display a much flatter radial profile: namely, satellites selected above a minimum stellar mass exhibit both smaller halo-centric distances and longer survival times in the full-physics simulations compared to their dark-matter only analogues. We then divide the TNG satellites into those which possess TNG-Dark counterparts and those which do not, and develop models for the radial positions of each. We find the satellites with TNG-Dark counterparts are displaced towards the halo centre in the full-physics simulations, and this difference has a power-law behaviour with radius. For the ‘orphan’ galaxies without TNG-Dark counterparts, we consider the shape of their radial distribution and provide a model for their motion over time, which can be used to improve the treatment of satellite galaxies in semi-analytic and semi-empirical models of galaxy formation.

Modelling globular clusters in the TNG50 simulation: predictions from dwarfs to giant galaxies

“…An interesting path forward is to use cosmological simulations of dwarf galaxies in high density environments to understand the connection between GCs, dwarf galaxies and their dark matter halos. This is particularly appealing since hydrodynamical cosmological simulations of representative volumes of the Universe have been powerful tools to understand and model the evolution of satellite dwarfs and their properties -such as color, mass content, morphology -in the environments of groups and clusters (Sales et al 2015;Yun et al 2019;Joshi et al 2020;Vogelsberger et al 2020;Donnari et al 2021a;Engler et al 2021a;Joshi et al 2021) creating a realistic population of satellite dwarfs in good agreement with observations (Donnari et al 2021b;Engler et al 2021b;Riggs et al 2022). However, the spatial and mass resolution of such simulations is too coarse to directly resolve the process of GC formation.…”

Merger-tree-based Galaxy Matching: A Comparative Study across Different Resolutions

“…In their highestresolution run, TNG50, a convergence test was conducted on morphological properties such as galaxy sizes, disk heights, and kinematics (Pillepich et al 2019). Comparisons of various other properties, such as stellar morphologies and star-forming activities (Zanisi et al 2021) and the radial distribution of satellite galaxies (Riggs et al 2022), with simulations of different resolutions within the TNG suite have also been performed.…”