The connection between surface brightness and satellite systems for central galaxies through Illustris TNG

TL;DR

This study uses the Illustris TNG-100 simulation to explore how surface brightness in central galaxies relates to their satellite systems, revealing differences in satellite numbers, velocities, and rotation patterns between low- and high-surface-brightness galaxies.

Contribution

It provides new insights into the connection between surface brightness and satellite dynamics, highlighting the role of merger history and satellite rotation in galaxy formation.

Findings

LSBGs have more satellites with higher velocity dispersion.

A continuous relation exists between satellite number and surface brightness.

Satellite systems in LSBGs tend to counter-rotate relative to the primary galaxy.

Abstract

We analyse different properties of central low-surface-brightness galaxies (LSBGs) and their satellite systems using the simulation Illustris TNG-100, in order to deepen our understanding of the formation mechanism of LSBGs in a $\Lambda$CDM cosmology. We find differences in the spin and the concentrations of the LSBGs haloes and the host haloes of high-surface-brightness galaxies (HSBGs), consistent with previous studies. By analysing their spatial and kinematical distribution of satellites, we find that LSBGs tend to have a larger number of satellites than HSBGs and with a larger velocity dispersion. Moreover, we obtain a continuous relation between the number of satellites and surface brightness, particularly for massive central galaxies. We also find a relation between surface brightness and the relative tangential velocity of the satellites. For a given stellar mass, the existence of LSBGs is strongly correlated with their satellite system dominated by rotation. Furthermore, the satellite system is systematically in counter-rotation with respect to the primary disc in LSBGs. We propose that this fact reflects that these galaxies have not experienced a significantly high rate of mergers, which are more likely associated with radial orbits expected in systems of galaxies with a high surface brightness.