Massive disk galaxies with high surface brightness plus low surface brightness stellar disks, hosted by massive dark matter halo -- a TNG50 simulation study

TL;DR

This study uses the TNG50 simulation to analyze massive disk galaxies with both high and low surface brightness stellar disks, demonstrating that such complex structures can form in cosmological models and match observational properties.

Contribution

The paper presents the first detailed simulation-based analysis of massive galaxies with combined high and low surface brightness disks, aligning with observed galaxy features.

Findings

Massive double-exponential disk galaxies are hosted by ~10^12 M_sun dark matter haloes.

Maximum rotation velocities range between 300-500 km/s.

Stellar-to-dark matter mass ratios are between 0.04 and 0.46.

Abstract

We study massive disk galaxies (total stellar mass$>=10^{11}$ $\mathrm{M_{\odot}}$) from IllustrisTNG50 simulation, and perform 2-D structural decomposition of the galaxies using their idealised, synthetic SDSS images for z=0. We find an interesting sample of galaxies having a central high surface brightness (HSB) stellar disk, surrounded by an extended low surface brightness (LSB) stellar disk, similar to giant LSB galaxies. These massive, double-exponential disk galaxies are found to be hosted by dark matter haloes of $\sim 10^{12} \mathrm{M_{\odot}}$ in agreement to observations of such galaxies. Their maximum rotation velocity, an approximate measure of their dynamical mass, lies within $\sim$ (300-500) km/s. The stellar-to-dark matter mass ratio and the baryon-to-dark matter mass ratio of the sample lies in the range of $\sim$ (0.04 - 0.46) and $\sim$ (0.07 - 0.47) respectively. Our results show that cosmological simulations are able to form disc galaxies with HSB plus LSB disks, as in observations.