2001/04/02 by Motohiro Enoki, Fumio Takahara, Yutaka Fujita
Physics and Astronomy · #Accretion (finance) #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Cluster (spacecraft) #Fundamental plane (elliptical galaxies) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Lenticular galaxy #Luminosity #Physics #Scaling #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.1086/321544
published as Astrophys.J. 556 (2001) 77 · 16 pages, 14 eps-figures. Accepted for publication in ApJ
arxiv created 2001/04/02 · openalex publication_date 2001/07/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate statistical properties of galaxy clusters in the context of a hierarchical clustering scenario, taking into account their formation epoch distribution; this study is motivated by the recent finding by Fujita and Takahara that X-ray clusters form a fundamental plane in which the mass and the formation epoch are regarded as two independent parameters. Using the formalism that discriminates between major mergers and accretion, the epoch of a cluster formation is identified with that of the last major merger. Since tiny mass accretion following formation does not much affect the core structure of clusters, the properties of X-ray emission from clusters are determined by the total mass and density at their formation time. Under these assumptions, we calculate X-ray luminosity and temperature functions of galaxy clusters. We find that the behavior of the luminosity function differs from the model that does not take into account formation epoch distribution; the behavior of the temperature function, however, is not much different. In our model, the luminosity function is shifted to a higher luminosity and shows no significant evolution up to z ~ 1, independent of cosmological models. The clusters are populated on the temperature-luminosity plane, with a finite dispersion. Since the simple scaling model in which the gas temperature is equal to the virial temperature fails to reproduce the observed luminosity-temperature relation, we also consider a model that takes into account the effects of preheating. The preheating model reproduces the observations much more accurately.