A line-of-sight galaxy cluster collision: Simulated X-RAY observations

J. A. Zuhone, P. M. Ricker, D. Q. Lamb, H. Y. Karen Yang

Research output: Contribution to journalArticlepeer-review


Several lines of evidence have suggested that the galaxy cluster Cl 0024+17, an apparently relaxed system, is actually a collision of two clusters, the interaction occurring along our line of sight. In this paper, we present a high-resolution N-body/hydrodynamics simulation of such a collision. We have created mock X-ray observations of our simulated system using MARX, a program that simulates the on-orbit performance of the Chandra X-ray Observatory. We analyze these simulated data to generate radial profiles of the surface brightness and temperature. At later times, t = 2.0-3.0 Gyr after the collision, the simulated surface brightness profiles are better fit by a superposition of two β-model profiles than a single profile, in agreement with the observations of Cl 0024+17. In general, due to projection effects, much of the post-collision density and temperature structure of the clusters is not seen in the observations. In particular, the observed temperatures from spectral fitting are much lower than the temperature of the hottest gas. We determine from our fitted profiles that if the system is modeled as a single cluster, the hydrostatic mass estimate is a factor 2-3 less than the actual mass, but if the system is modeled as two galaxy clusters in superposition, a hydrostatic mass estimation can be made which is accurate to within 10%. We examine some implications of these results for galaxy cluster X-ray surveys.

Original languageEnglish (US)
Pages (from-to)1004-1014
Number of pages11
JournalAstrophysical Journal
Issue number2
StatePublished - 2009


  • Galaxies: clusters: general
  • Methods: N-body simulations
  • X-rays: galaxies: clusters

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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