Gas stripping in galaxy clusters: a new SPH simulation approach^*

¹ Astronomical Institute, Academy of Sciences of the Czech Republic, Boční II 1401, 141 31 Prague 4, Czech Republic e-mail: [jachym;palous]@ig.cas.cz
² Observatoire Astronomique de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France e-mail: koppen@astro.u-strasbg.fr
³ International Space University, Parc d'Innovation, 1 rue Jean-Dominique Cassini, 67400 Illkirch-Graffenstaden, France
⁴ Institut für Theoretische Physik und Astrophysik, Universität Kiel, 24098 Kiel, Germany
⁵ Observatoire de Paris, LERMA, 61 Av. de l'Observatoire, 75014 Paris, France

Received: 25 September 2006
Accepted: 22 May 2007

Abstract

Aims.The influence of a time-varying ram pressure on spiral galaxies in clusters is explored with a new simulation method based on the N-body SPH/tree code GADGET.

Methods.We have adapted the code to describe the interaction of two different gas phases, the diffuse hot intracluster medium (ICM) and the denser and colder interstellar medium (ISM). Both the ICM and ISM components are introduced as SPH particles. As a galaxy arrives on a highly radial orbit from outskirts to cluster center, it crosses the ICM density peak and experiences a time-varying wind.

Results.Depending on the duration and intensity of the ISM–ICM interaction, early and late type galaxies in galaxy clusters with either a large or small ICM distribution are found to show different stripping efficiencies, amounts of reaccretion of the extra-planar ISM, and final masses. We compare the numerical results with analytical approximations of different complexity and indicate the limits of the Gunn & Gott simple stripping formula.

Conclusions.Our investigations emphasize the role of the galactic orbital history to the stripping amount. We discuss the contribution of ram pressure stripping to the origin of the ICM and its metallicity. We propose gas accumulations like tails, filaments, or ripples to be responsible for stripping in regions with low overall ICM occurrence.