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Title: Mass estimates of X-ray clusters

Abstract

We use cosmological gasdynamic simulations to investigate the accuracy of galaxy cluster mass estimates based on X-ray observations. The experiments follow the formation of clusters in different cosmological models and include the effects of gravity, pressure gradients, and hydrodynamical shocks. A subset of our ensemble also allows for feedback of mass and energy from galactic winds into the intracluster medium. We find that mass estimates based on the hydrostatic, isothermal {beta}-model are remarkably accurate when evaluated at radii where the cluster mean density is between 500 and 2500 times the critical density. At lower densities, radial temperature information becomes important. In the quoted radial regime, the distribution of the estimated-to-true mass ratio, derived from 174 artificial images constructed from the simulations, is nearly unbiased and has a standard deviation of 14{percent}{endash}29{percent}. The scatter can be considerably reduced (to 8{percent}{endash}15{percent}) by using an alternative mass estimator that exploits the tightness of the mass-temperature relation found in the simulations. The improvement over {beta}-model estimates is due to the elimination of the variance contributed by the gas outer slope parameter. We discuss these findings and their implications for recent measurements of cluster baryon fractions. {copyright} {ital 1996 The American Astronomical Society.}

Authors:
 [1];  [2];  [3]
  1. Physics Department, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States)
  2. NASA/Fermilab Astrophysics Center, Batavia, Illinois 60510-0500 (United States)
  3. Steward Observatory, University of Arizona, Tucson, Arizona 85721 (United States)
Publication Date:
OSTI Identifier:
467176
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 469; Journal Issue: 2; Other Information: PBD: Oct 1996
Country of Publication:
United States
Language:
English
Subject:
66 PHYSICS; GALAXY CLUSTERS; MASS; HYDRODYNAMICS; X RADIATION; NONLUMINOUS MATTER; COMPUTERIZED SIMULATION; COSMOLOGICAL MODELS

Citation Formats

Evrard, A.E., Metzler, C.A., and Navarro, J.F.. Mass estimates of X-ray clusters. United States: N. p., 1996. Web. doi:10.1086/177798.
Evrard, A.E., Metzler, C.A., & Navarro, J.F.. Mass estimates of X-ray clusters. United States. doi:10.1086/177798.
Evrard, A.E., Metzler, C.A., and Navarro, J.F.. Tue . "Mass estimates of X-ray clusters". United States. doi:10.1086/177798.
@article{osti_467176,
title = {Mass estimates of X-ray clusters},
author = {Evrard, A.E. and Metzler, C.A. and Navarro, J.F.},
abstractNote = {We use cosmological gasdynamic simulations to investigate the accuracy of galaxy cluster mass estimates based on X-ray observations. The experiments follow the formation of clusters in different cosmological models and include the effects of gravity, pressure gradients, and hydrodynamical shocks. A subset of our ensemble also allows for feedback of mass and energy from galactic winds into the intracluster medium. We find that mass estimates based on the hydrostatic, isothermal {beta}-model are remarkably accurate when evaluated at radii where the cluster mean density is between 500 and 2500 times the critical density. At lower densities, radial temperature information becomes important. In the quoted radial regime, the distribution of the estimated-to-true mass ratio, derived from 174 artificial images constructed from the simulations, is nearly unbiased and has a standard deviation of 14{percent}{endash}29{percent}. The scatter can be considerably reduced (to 8{percent}{endash}15{percent}) by using an alternative mass estimator that exploits the tightness of the mass-temperature relation found in the simulations. The improvement over {beta}-model estimates is due to the elimination of the variance contributed by the gas outer slope parameter. We discuss these findings and their implications for recent measurements of cluster baryon fractions. {copyright} {ital 1996 The American Astronomical Society.}},
doi = {10.1086/177798},
journal = {Astrophysical Journal},
number = 2,
volume = 469,
place = {United States},
year = {Tue Oct 01 00:00:00 EDT 1996},
month = {Tue Oct 01 00:00:00 EDT 1996}
}
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