EDP Sciences
Free Access
Issue
A&A
Volume 398, Number 3, February II 2003
Page(s) L35 - L39
Section Letters
DOI https://doi.org/10.1051/0004-6361:20021877
Published online 28 January 2003


A&A 398, L35-L39 (2003)
DOI: 10.1051/0004-6361:20021877

Letter

Reproducing the entropy structure in galaxy groups

A. Finoguenov1, S. Borgani2, 3, L. Tornatore2 and H. Böhringer1

1  Max-Planck Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany
2  Dipartimento di Astronomia, Università di Trieste, via Tiepolo 11, 34131 Trieste, Italy
3  INAF, Istituto Nazionale di Astrofisica; INFN, Sezione di Trieste, Trieste, Italy

(Received 24 October 2002 / Accepted 19 December 2002 )

Abstract
We carry out a comparison between observations and hydrodynamic simulations of entropy profiles of groups and clusters of galaxies. We use the Tree+SPH GADGET code to simulate four halos of sizes in the $M_{500}=1.0{-}16\times10^{13}~h^{-1}\,M_{\odot}$ range, corresponding to poor groups up to Virgo-like clusters. We concentrate on the effect of introducing radiative cooling, star formation, and a variety of non-gravitational heating schemes on the entropy structure and the stellar fraction. We show that all the simulations result in a correct entropy profile for the Virgo-like cluster. With the heating energy budget of ~0.7 keV/particle injected at  $z_{\rm h}=3$, we are also able to reproduce the entropy profiles of groups. We obtain the flat entropy cores as a combined effect of preheating and cooling, while we achieve the high entropy at outskirts by preheating. The resulting baryon fraction locked into stars is in the 25-30% range, compared to 35-40% in the case of no preheating. Heating at higher redshift, $z_{\rm h}=9$, strongly delays the star-formation, but fails to produce a sufficiently high specific entropy.


Key words: clusters: cosmology -- cosmic star-formation

Offprint request: A. Finoguenov, alexis@xray.mpe.mpg.de

SIMBAD Objects



© ESO 2003

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.