Volume 398, Number 3, February II 2003
|Page(s)||L35 - L39|
|Published online||28 January 2003|
Letter to the Editor
Reproducing the entropy structure in galaxy groups
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
Corresponding author: A. Finoguenov, firstname.lastname@example.org
Accepted: 19 December 2002
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 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 , 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, , strongly delays the star-formation, but fails to produce a sufficiently high specific entropy.
Key words: clusters: cosmology / cosmic star-formation
© ESO, 2003
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