Exploring the effect of baryons on the radial distribution of satellite galaxies with GAMA and IllustrisTNG. Issue 4 (15th June 2022)

• Record Type: Journal Article
• Authors: Riggs, Stephen D; Loveday, Jon; Thomas, Peter A; Pillepich, Annalisa; Nelson, Dylan; Holwerda, Benne W
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 514:Issue 4(2022)
• Page Start: 4676
• Page End: 4695
• Publication Date: 2022-06-15
• Subjects: methods: numerical -- galaxies: groups: general -- galaxies: haloes; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac1591
• Languages: English
• ISSNs: 0035-8711

Abstract

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 $12.0 \le \log _{10} (\mathcal {M}_h / h^{-1} \, \mathrm{M}_{\odot }) \lt 14.8$ 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 normalized 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 halocentric 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.