The Local Volume HI Survey: star formation properties

TL;DR

This study analyzes the relationship between HI gas distribution and star formation in 82 galaxies from the Local Volume HI Survey, revealing weak links between HI properties and star formation, but a strong correlation with stellar mass density.

Contribution

It provides a comprehensive multi-wavelength dataset for the LVHIS sample and investigates the detailed correlations between HI gas, star formation, and stellar mass in galaxy outskirts.

Findings

Weak correlation between total HI mass and SFR when considering surface densities.

Strong correlation between SFR surface density and stellar mass surface density.

No link found between HI warps and star forming efficiencies.

Abstract

We built a multi-wavelength dataset for galaxies from the Local Volume HI Survey (LVHIS), which comprises 82 galaxies. We also select a sub-sample of ten large galaxies for investigating properties in the galactic outskirts. The LVHIS sample covers nearly four orders of magnitude in stellar mass and two orders of magnitude in HI mass fraction (fHI). The radial distribution of HI gas with respect to the stellar disc is correlated with fHI but with a large scatter. We confirm the previously found correlations between the total HI mass and star formation rate (SFR), and between HI surface densities and SFR surface densities beyond R25. However, the former correlation becomes much weaker when the average surface densities rather than total mass or rate are considered, and the latter correlation also becomes much weaker when the effect of stellar mass is removed or controlled. Hence the link between SFR and HI is intrinsically weak in these regions, consistent with what was found on kpc scales in the galactic inner regions. We find a strong correlation between the SFR surface density and the stellar mass surface density, which is consistent with the star formation models where the gas is in quasi-equilibrium with the mid-plane pressure. We find no evidence for HI warps to be linked with decreasing star forming efficiencies.