Open AccessProperties of the double β model for intracluster gas
Author(s) -
Xue YanJie,
Wu XiangPing
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03753.x
Subject(s) - physics , surface brightness , hydrostatic equilibrium , rosat , astrophysics , cluster (spacecraft) , surface (topology) , intracluster medium , statistical physics , galaxy cluster , galaxy , astronomy , geometry , mathematics , computer science , programming language
We present an extensive study of the double β model for the X‐ray surface brightness profiles of clusters, and derive analytically the gas density and total masses of clusters under the hydrostatic equilibrium hypothesis. It is shown that the employment of the double β model instead of the conventional single β model can significantly improve the goodness‐of‐fit to the observed X‐ray surface brightness profiles of clusters, which will in turn lead to a better determination of the gas and total mass distributions in clusters. In particular, the observationally fitted β parameter for the extended component in a double β model may become larger. This opens a new possibility of resolving the long‐standing β discrepancy for clusters. Using an ensemble of 33 ROSAT PSPC observed clusters drawn from the Mohr, Mathiesen & Evrard sample, we find that the asymptotic value of β fit is 0.83±0.33 at large radii, consistent with both the average spectroscopic parameter β spec =0.78±0.37 and the result given by numerical simulations.