Investigating the H i mass-size relation using the Simba cosmological simulations

TL;DR

This study uses Simba cosmological simulations to show that the H I mass-size relation in galaxies is robust against different feedback mechanisms, maintaining a consistent power-law form aligned with observations.

Contribution

It demonstrates that the H I mass-size relation persists across various feedback models, highlighting its fundamental nature in galaxy structure.

Findings

The H I mass-size relation remains intact despite feedback variations.

Outer H I profiles are well approximated by exponential functions.

The relation's parameters are consistent with empirical measurements.

Abstract

Observational studies have established a remarkably tight power-law relationship between the H I masses and sizes of late-type galaxies, known as the H I mass-size relation. This relation has been shown to persist across various models of a galaxy's H I surface density profile. Using the Simba cosmological simulations, we investigate the robustness of this relation under different feedback prescriptions, including cases where specific feedback mechanisms are absent. While the global properties of galaxies are significantly affected by changes in feedback, the H I mass-size relation remains intact. Moreover, its parameters consistently align with the best available empirical measurements. We analyze the H I mass distributions of galaxies and demonstrate that, regardless of the feedback scenario, galaxies within a given H I mass bin exhibit outer H I radial profiles well approximated by an exponential function. Furthermore, the exponential decline rate remains remarkably similar across different physical prescriptions. We attribute the persistence of the H I mass-size relation to this inherent self-similarity in the H I mass distributions.