The Distribution of Satellite Galaxies in the TNG100 Simulation

TL;DR

This study analyzes the spatial distribution of satellite galaxies in the TNG100 simulation, revealing that their distribution generally follows an NFW profile with varying concentrations depending on satellite brightness, color, and accretion history.

Contribution

It provides a detailed comparison of satellite galaxy distributions with host mass density profiles, highlighting differences based on satellite properties and accretion times in the TNG100 simulation.

Findings

Satellite distributions are well-fitted by NFW profiles with lower concentration than host mass density.

Bright and faint satellites show different concentration parameters in their distributions.

Satellite color and accretion time influence their spatial distribution relative to host mass density.

Abstract

We investigate the spatial distribution of the satellites of isolated host galaxies in the TNG100 simulation. In agreement with a previous, similar analysis of the Illustris-1 simulation, the satellites are typically poor tracers of the mean host mass density. Unlike the Illustris-1 satellites, here the spatial distribution of the complete satellite sample is well-fitted by an NFW profile; however, the concentration is a factor of ~2 lower than that of the mean host mass density. The spatial distribution of the brightest 50% and faintest 50% of the satellites are also well-fitted by NFW profiles, but the concentrations differ by a factor of ~2. When the sample is subdivided by host color and luminosity, the number density profiles for blue satellites generally fall below the mean host mass density profiles while the number density profiles for red satellites generally rise above the mean host mass density profiles. These opposite, systematic offsets combine to yield a moderately good agreement between the mean mass density profile of the brightest blue hosts and the corresponding number density profile of their satellites. Lastly, we subdivide the satellites according to the redshifts at which they joined their hosts. From this, we find that neither the oldest one third of the satellites nor the youngest one third of the satellites faithfully trace the mean host mass density.