2001/01/31 by Haiguang Xu, Guangxue Jin, Guang-xue Jin +2 · 1 citation
Mathematics · Physics and Astronomy · #Astrophysics #Astrophysics and Star Formation Studies #Cluster (spacecraft) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Hydrostatic equilibrium #Intracluster medium #Isothermal process #Mathematics #Physics #ROSAT #Scaling #Statistical physics #Stellar, planetary, and galactic studies #Surface brightness #Thermodynamics #astro-ph
paper · pdf · doi:10.1086/320662
15 pages, 2 tables, 4 figures; accepted for publication in ApJ
arxiv created 2001/01/31 · openalex publication_date 2001/05/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a new investigation of the mass-temperature ( M tot - T X ) relation of 22 nearby clusters based on the analysis of their ROSAT X-ray surface brightness profiles ( S X ) and their ASCA emission-weighted temperatures. Two methods of the cluster mass estimations are employed and their results are compared: (1) the conventional β-model for gas distribution along with the isothermal and hydrostatic equilibrium assumptions, and (2) the NFW profile for dark matter distribution whose characteristic density and length are determined by the observed S X ( r ). These two models yield essentially the same goodness of fits for S X ( r ) and the similar M tot - T X relations, with the latter demonstrating a significant departure from the simple gravitational scaling of M tot ∝ T . It is also shown that the best-fit M tot - T X relations could be reconciled with the theoretical expectation if the low-temperature clusters ( T X < 3.5 keV) are excluded from the list, which lends support to the scenario that the intracluster medium is preheated in the early phase of cluster formation. Together with the entropy-temperature distribution, the existence of a similarity break at T X = 3-4 keV in the dynamical scaling relations for galaxy clusters has been confirmed.