Neutral Hydrogen content of dwarf galaxies in different environments

TL;DR

This study investigates how environment influences the neutral hydrogen content in dwarf galaxies by combining deep FAST observations with existing surveys, revealing environmental effects on gas content and galaxy evolution.

Contribution

It introduces a method of using deep FAST observations to study low HI content dwarf galaxies across environments, improving understanding of gas stripping processes.

Findings

Positive correlation between HI mass and stellar mass in dwarfs

Decreased HI-to-stellar mass ratio with increasing environment density

Steeper gas-stripping slope observed compared to simulations

Abstract

Environments play an important role in galaxy formation and evolution, particularly in regulating the content of neutral gas. However, current HI surveys have limitations in their depth, which prevents them from adequately studying low HI content galaxies in high-density regions. In this study, we address this issue by employing the Five-hundred-meter Aperture Spherical radio Telescope (FAST) with extensive integration times to complement the relatively shallow Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) HI survey. This approach allows us to explore the gas content of dwarf galaxies across various environments. We observe a positive relationship between HI mass and stellar mass in dwarf galaxies, with a well-defined upper boundary for HI mass that holds true in both observations and simulations. Furthermore, we find a decrease in the HI-to-stellar mass ratio ($\rm M_{\rm HI}/M_*$) as the density of the environment increases, irrespective of whether it is determined by the proximity to the nearest group or the projected number density. Comparing our observations to simulations, we note a steeper slope in the relationship, indicating a gradual gas-stripping process in the observational data. Additionally, we find that the scaling relation between the $\rm M_{\rm HI}/M_*$ and optical properties can be improved by incorporating galaxy environments.