Ram pressure stripping of disc galaxies orbiting in clusters. I. Mass and radius of the remaining gas disc

TL;DR

This study uses 3D hydrodynamical simulations to analyze how ram pressure stripping affects the gas disc of a galaxy in a cluster, comparing results with classical analytical models.

Contribution

First 3D hydrodynamical simulations of ram pressure stripping in galaxy clusters, evaluating the accuracy of classical analytical estimates for gas disc evolution.

Findings

Analytical estimate predicts gas disc radius well.

Gas mass loss occurs more slowly than predicted.

Rapid ram pressure increases can cause larger disc radii than expected.

Abstract

We present the first 3D hydrodynamical simulations of ram pressure stripping of a disc galaxy orbiting in a galaxy cluster. Along the orbit, the ram pressure that this galaxy experiences varies with time. In this paper, we focus on the evolution of the radius and mass of the remaining gas disc and compare it with the classical analytical estimate proposed by Gunn & Gott 1972. We find that this simple estimate works well in predicting the evolution of the radius of the remaining gas disc. Only if the ram pressure increases faster than the stripping timescale, the disc radius remains larger than predicted. However, orbits with such short ram pressure peaks are unlikely to occur in other than compact clusters. Unlike the radius evolution, the mass loss history for the galaxy is not accurately described by the analytical estimate. Generally, in the simulations the galaxy loses its gas more slowly than predicted.