Cluster scaling relations from cosmological hydrodynamic simulations in a dark-energy dominated universe

¹ IAS, CNRS & Université Paris Sud, Bâtiment 121, 91405 Orsay, France e-mail: nabila.aghanim@ias.u-psud.fr
² Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal e-mail: asilva@astro.up.pt
³ Department of Applied Mathematics and Theoretical Physics, Wilberforce Road, Cambridge, CB3 0WA, UK e-mail: nunes@damtp.cam.ac.uk

Received: 28 July 2008
Accepted: 20 November 2008

Abstract

Context. Clusters are potentially powerful tools for cosmology provided their observed properties, such as the Sunyaev-Zel'dovich (SZ) or X-ray signals, can be translated into physical quantities like mass and temperature. Scaling relations are the appropriate means to perform this translation. It is, therefore, important to understand their evolution and their modifications with respect to the physics and to the underlying cosmology.

Aims. In this spirit, we investigate the effect of dark energy on the X-ray and SZ scaling relations. The study is based on the first hydro-simulations of cluster formation for diferent models of dark energy. We present results for four dark-energy models which differ from each other by their equations-of-state parameter, w. Namely, we use a cosmological constant model (as a reference), a perfect fluid with constant equation of state parameter and one with and a scalar field model (or quintessence) with varying w.

Methods. We generate N-body/hydrodynamic simulations that include radiative cooling with the public version of the Hydra code, modified to consider an arbitrary dark-energy component. We produce cluster catalogues for the four models and derive the associated X-ray and SZ scaling relations.

Results. We find that dark energy has little effect on scaling laws, making it safe to use the standard ΛCDM scalings for conversion of observed quantities into cluster temperatures and masses.