The effect of the environment on the HI scaling relations

TL;DR

This study examines how the environment influences HI scaling relations in galaxies, revealing that cluster galaxies have lower gas content and that ram-pressure stripping explains these differences better than starvation, with potential for a new HI deficiency proxy.

Contribution

It demonstrates the environmental dependence of HI scaling relations and shows that ram-pressure stripping, not starvation, explains gas depletion in cluster galaxies, proposing a new proxy for HI deficiency.

Findings

Cluster galaxies have lower HI content than field galaxies.

Ram-pressure stripping explains gas loss better than starvation.

The HI gas fraction plane can serve as an HI deficiency proxy.

Abstract

We use a volume-, magnitude-limited sample of nearby galaxies to investigate the effect of the environment on the HI scaling relations. We confirm that the HI-to-stellar mass ratio anti correlates with stellar mass, stellar mass surface density and NUV-r colour across the whole range of parameters covered by our sample (10^9 <M*<10^11 Msol, 7.5 <mu*<9.5 Msol kpc^-2, 2<NUV-r<6 mag). These scaling relations are also followed by galaxies in the Virgo cluster, although they are significantly offset towards lower gas content. Interestingly, the difference between field and cluster galaxies gradually decreases moving towards massive, bulge-dominated systems. By comparing our data with the predictions of chemo-spectrophotometric models of galaxy evolution, we show that starvation alone cannot explain the low gas content of Virgo spirals and that only ram-pressure stripping is able to reproduce our findings. Finally, motivated by previous studies, we investigate the use of a plane obtained from the relations between the HI-to-stellar mass ratio, stellar mass surface density and NUV-r colour as a proxy for the HI deficiency parameter. We show that the distance from the `HI gas fraction plane' can be used as an alternative estimate for the HI deficiency, but only if carefully calibrated on pre-defined samples of `unperturbed' systems.