Ram pressure histories of cluster galaxies

TL;DR

This study reconstructs the history of ram pressure experienced by cluster galaxies, revealing that a significant fraction undergo strong ram-pressure stripping, especially in cluster cores, impacting galaxy evolution.

Contribution

It combines simulations and analytic models to map the present-day distribution and history of ram pressure on cluster galaxies, a novel approach in this context.

Findings

About 25% of galaxies face strong ram-pressure stripping.

Strong ram-pressure occurs mainly in cluster cores.

Over 64% of cluster galaxies experienced significant ram-pressure since accretion.

Abstract

Ram pressure stripping can remove significant amounts of gas from galaxies that orbit in clusters and massive groups, and thus has a large impact on the evolution of cluster galaxies. In this paper, we reconstruct the present-day distribution of ram-pressure, and the ram pressure histories of cluster galaxies. To this aim, we combine the Millennium Simulation and an associated semi-analytic model of galaxy evolution with analytic models for the gas distribution in clusters. We find that about one quarter of galaxies in massive clusters are subject to strong ram-pressures that are likely to cause an expedient loss of all gas. Strong ram-pressures occur predominantly in the inner core of the cluster, where both the gas density and the galaxy velocity are higher. Since their accretion onto a massive system, more than 64 per cent of galaxies that reside in a cluster today have experienced strong ram-pressures of $>10^{-11}$ dyn cm$^{-2}$ which most likely led to a substantial loss of the gas.