The Role of Ram Pressure Stripping in the Quenching of Cluster Star Formation

TL;DR

This paper investigates how ram pressure stripping influences galaxy quenching in clusters by modeling its effects and comparing with observations, highlighting the need for more data to distinguish between models.

Contribution

It introduces a new model of ram pressure stripping using the accretion shock radius and compares it with simpler models and observations.

Findings

Current data cannot strongly discriminate between ram pressure models.

The accretion shock radius is a key factor in modeling ram pressure effects.

Future observations are needed to better constrain ram pressure stripping processes.

Abstract

Recent observations of galaxy clusters have shown that environmental effects apparently associated with the cluster begin to lower the star formation rates of galaxies at distances as great as three times the cluster virial radius. These observations may indicate preprocessing of cluster galaxies in groups or in the cluster core for galaxies on highly elliptical orbits, but may also imply that the environmental effects due to the cluster are directly affecting galaxies on their first infall. To explore these issues, we investigate different models of ram pressure stripping as it acts on satellite galaxies in clusters, and compare to observations of the radial star formation gradient in clusters. We calculate the location of the accretion shock around model clusters, and use this as the radius of onset of ram pressure stripping in the GALFORM semi-analytic model of galaxy formation. Comparison of the results of our model, and previously considered, simpler ram pressure models, with recent observations indicates that current data is unable to strongly discriminate between models of ram pressure stripping due to the complex interplay of preprocessing effects at work. However, future observations of a larger sample of clusters will likely be able to place stronger constraints on the process of ram pressure stripping and its role in shaping radial trends in and around clusters.