The influence of angular momentum and environment on the HI gas of late-type galaxies

TL;DR

This study analyzes how angular momentum and environment affect the HI gas content and morphology of late-type galaxies, revealing environmental impacts on gas stability and galaxy structure.

Contribution

It provides new insights into the $j_b - M_b$ relation, the environmental influence on the $f_{atm} - q$ relation, and links galaxy morphology with angular momentum and gas fraction.

Findings

Power law $j_b \\propto M_b^{0.55}$ fits data well

Galaxies with close neighbors show larger scatter in $f_{atm} - q$

Decreasing B/T ratio correlates with higher disc stability and HI fraction

Abstract

We use high-resolution HI data from the WHISP survey to study the HI and angular momentum properties of a sample of 114 late-type galaxies. We explore the specific baryonic angular momentum -- baryonic mass ($j_b - M_b$) relation, and find that an unbroken power law of the form $j_b \propto M_b^{0.55 \pm 0.02}$ fits the data well, with an intrinsic scatter of $\sim 0.13 \pm 0.01$ dex. We revisit the relation between the atomic gas fraction, $f_{atm}$, and the integrated atomic stability parameter $q$ (the $f_{atm} - q$ relation), originally introduced by Obreschkow et al., and probe this parameter space by populating it with galaxies from different environments, in order to study the influence of the environment on their $j_b$, $f_{atm}$ and $q$ values. We find evidence that galaxies with close neighbours show a larger intrinsic scatter about the $f_{atm} - q$ relation compared to galaxies without close-neighbours. We also find enhanced SFR among the deviating galaxies with close neighbours. In addition, we use the bulge-to-total (B/T) ratio as a morphology proxy, and find a general trend of decreasing B/T values with increasing disc stability and HI fraction in the $f_{atm} - q$ plane, indicating a fundamental link between mass, specific angular momentum, gas fraction and morphology of galaxies.