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

¹ Observatorio Astronómico de Córdoba, Universidad Nacional de Córdoba, Córdoba X5000BGR, Argentina
² Instituto de Astronomía Teórica y Experimental, UNC-CONICET, Córdoba X5000BGR, Argentina
³ Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA
⁴ Instituto de Astronomía y Física del Espacio, CONICET-UBA, 1428 Buenos Aires, Argentina
⁵ Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile

^⋆ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 26 September 2025
Accepted: 8 February 2026

Abstract

We analysed different properties of central low-surface-brightness galaxies (LSBGs) and their satellite systems using the simulation TNG100 in order to deepen our understanding of the formation mechanism of LSBGs in a Λ cold dark matter cosmology. We find differences in the spin and the concentrations of the LSBG haloes and the host haloes of high-surface-brightness galaxies (HSBGs) consistent with previous studies. From analysis of the spatial and kinematical distribution of satellites in the central LSBGs, we find that they tend to have a larger number of satellites than HSBGs with a larger velocity dispersion. Moreover, we obtained a continuous relation between the number of satellites and surface brightness, particularly for massive central galaxies. We also found 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 the radial orbits expected in systems of galaxies with a high surface brightness.