  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 $12.0 \leq \log_{10} (\mathcal{M}_h / h^{-1}
\mathrm{M}_{\odot}) < 14.8$ 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.

Astrophysics of Galaxies;Cosmology and Nongalactic Astrophysics