Volume 407, Number 2, August IV 2003
|Page(s)||437 - 451|
|Section||Cosmology (including clusters of galaxies)|
|Published online||17 November 2003|
A study of dark matter halos and gas properties in clusters of galaxies from ROSAT data*
ESO-European Southern Observatory, Karl-Schwarzschild Str. 2, 85748 Garching b. München, Germany
2 Institut d'Astrophysique de Paris, CNRS, 98bis Bd Arago, 75014 Paris, France
3 Instituto de Astrofísica de Andalucía (C.S.I.C.), Apartado 3004 , 18080 Granada, Spain
Corresponding author: R. Demarco, email@example.com
Accepted: 28 May 2003
Self-gravitating systems such as elliptical galaxies appear to have a constant integrated specific entropy and obey a scaling law relating their potential energy to their mass. These properties can be interpreted as due to the physical processes involved in the formation and evolution of these structures. Dark matter halos obtained through numerical simulations have also been found to obey a scaling law relating their potential energy to their mass with the same slope as for ellipticals, and very close to the expected value predicted by theory. Since the X-ray gas in clusters is weakly dissipative, we test here the hypothesis that it verifies similar properties. Comparable properties for the dark matter component are also investigated. With this aim, we have analyzed ROSAT-PSPC images of 24 clusters, and fit a Sérsic law to their X-ray surface brightness profiles. We found that: 1) the Sérsic law parameters (intensity, shape and scale) describing the X-ray gas emission are correlated two by two, with a strong correlation between the shape and scale parameters; 2) the hot gas in all these clusters roughly has the same integrated specific entropy, although a second order correlation between this integrated specific entropy and both the gas mass and the dynamical mass is observed; 3) a scaling law links the cluster potential energy to its total mass, with the same slope as that derived for elliptical galaxies and for dark matter halo simulations. Comparable relations are obtained for the dark matter component. All these correlations are probably the consequence of the formation and evolution processes undergone by clusters of galaxies.
Key words: cosmology: theory / cosmology: dark matter / galaxies: clusters: general / X-rays: galaxies: clusters
© 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.