Ram Pressure Stripping and ISM disc Truncation : Prediction vs. Observation

TL;DR

This study compares observed gas truncation radii in Virgo cluster galaxies undergoing ram pressure stripping with theoretical predictions, finding good agreement in active RPS cases but discrepancies elsewhere, highlighting the process's complexity.

Contribution

It evaluates the effectiveness of simple momentum transfer models in predicting RPS effects and identifies conditions where these models are reliable or need refinement.

Findings

Good agreement between predictions and observations in active RPS galaxies.

Discrepancies in early or late RPS stages or when other environmental effects are present.

Conventional RPS relations are broadly applicable but require careful consideration in complex environments.

Abstract

Ram pressure stripping (RPS) is known to be a key environmental effect that can remove interstellar gas from galaxies in a cluster. The RPS process is commonly described as a competition between the ram pressure by the intracluster medium (ICM) and the anchoring pressure on the interstellar medium (ISM) by the gravitational potential of a galaxy. However, the actual gas stripping process can be more complicated due to the complexity of gas physics such as compression and geometrical self-shielding as well as cooling and heating. In order to verify how well the observed signatures of the RPS process can be understood as simple momentum transfer, we compare the stripping radii of Virgo cluster galaxies in different stages of RPS measured from the HI observation with the predicted gas truncation radii for the given conditions. For the sample undergoing active RPS, we generally find good agreements between predictions and observations within a measurement uncertainty. On the other hand, galaxies likely in the early or later RPS stage and/or the ones with signs of environmental impacts other than RPS such as tidal interaction or starvation, show some discrepancies. Our results imply that the conventional RPS relation works reasonably well in a broad sense when RPS is the most dominant process and the galaxy is located where the surrounding environment can be well defined. Otherwise, more careful inspections on the second mechanism and local environment are required to assess the impact of RPS on the target.