Open AccessThe merger history of clusters and its effect on the X‐ray properties of the intracluster medium
Author(s) -
Rowley David R.,
Thomas Peter A.,
Kay Scott T.
Publication year - 2004
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 - 10.1111/j.1365-2966.2004.07941.x
Subject(s) - physics , intracluster medium , astrophysics , merge (version control) , redshift , cluster (spacecraft) , cosmology , luminosity , radiative transfer , galaxy cluster , galaxy , optics , computer science , information retrieval , programming language
We investigate the growth over time of 20 massive (>3 keV) clusters in a hydrodynamical simulation of the Λ cold dark matter cosmology with radiative cooling. The clusters show a variety of formation histories: some accrete most of their mass in major mergers; others, more gradually. During major mergers, the long‐term (temporally smoothed) luminosity increases such that the cluster moves approximately along the L X – T X relation; between times, it slowly decreases, tracking the drift of the L X – T X relation. We identify several different kinds of short‐term luminosity and temperature fluctuations associated with major mergers including double‐peaked mergers, in which the global intracluster medium merges first ( L X and T X increase together) and then the cluster cores merge ( L X increases and T X decreases). At both luminosity peaks, clusters tend to appear to be spherical and relaxed, which may lead to biases in high‐redshift, flux‐limited samples. There is no simple relationship between scatter in the L X – T X relation nor in the recent or overall merger activity or cluster formation time. The scatter in the L X – M and T X – M relations is reduced if properties are measured within R 500 rather than R vir .