The Local Volume H I Survey: star formation properties

We built a multiwavelength data set for galaxies from the Local Volume HI Survey (LVHIS), which comprises 82 galaxies. We also select a sub-sample of 10 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 H I mass fraction (f(H I)). The radial distribution of H I gas with respect to the stellar disc is correlated with f(H I) but with a large scatter. We confirm the previously found correlations between the total H I mass and star formation rate (SFR), and between H I surface densities and SFR surface densities beyond R-25. 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 H I is intrinsically weak in these regions, consistent with what was found on kiloparsecs 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 H I warps to be linked with decreasing star-forming efficiencies.