A History of HI Stripping in Virgo: A Phase-space View of VIVA Galaxies

TL;DR

This study uses phase-space analysis to trace the history of HI gas stripping in Virgo cluster galaxies, revealing different stages of infall and the influence of environmental interactions on gas loss and star formation.

Contribution

It introduces a phase-space method to effectively trace HI stripping histories and identifies the backsplash galaxy population in Virgo for the first time.

Findings

Early-stage HI stripping galaxies are in the first infall region.

Active stripping galaxies are near the cluster core or falling in.

Severely stripped, symmetric HI disks are found inside and outside the cluster.

Abstract

We investigate the orbital histories of Virgo galaxies at various stages of HI gas stripping. In particular, we compare the location of galaxies with different HI morphology in phase space. This method is a great tool for tracing the gas stripping histories of galaxies as they fall into the cluster. Most galaxies at the early stage of HI stripping are found in the first infall region of Virgo, while galaxies undergoing active HI stripping mostly appear to be falling in or moving out near the cluster core for the first time. Galaxies with severely stripped, yet symmetric, HI disks are found in one of two locations. Some are deep inside the cluster, but others are found in the cluster outskirts with low orbital velocities. We suggest that the latter group of galaxies belong to a "backsplash" population. These present the clearest candidates for backsplashed galaxies observationally identified to date. We further investigate the distribution of a large sample of HI-detected galaxies toward Virgo in phase space, confirming that most galaxies are stripped of their gas as they settle into the gravitational potential of the cluster. In addition, we discuss the impact of tidal interactions between galaxies and group preprocessing on the HI properties of the cluster galaxies, and link the associated star formation evolution to the stripping sequence of cluster galaxies.