Does Angular Momentum Regulate the Atomic Gas Content in HI-deficient Spirals?

The neutral atomic hydrogen (HI) content of spiral galaxies has been observed to vary with environment, with spirals residing in high-density environments being more HI-deficient. This can been explained by environmental effects such as ram pressure stripping and tidal interactions, which remove HI from the discs of galaxies. However, some spirals in low-density environments have also been observed to have relatively low HI mass fractions. The low densities of the Intra Galactic Medium and lack of nearby galaxies in such environments make ram pressure stripping and tidal interactions unlikely candidates of gas removal. What then could be making these spirals HI deficient? In this work, we show that for a sample of HI-deficient spirals from low-density environments, their specific angular momentum influences their HI gas content through its ability to regulate global star formation in their discs. We find that our sample of HI-deficient galaxies consistently follow the model predicted by Obreschkow et al., where the atomic gas fraction, in a symmetric equilibrium disc is a function of the global atomic stability parameter q, which depends on specific angular momentum.