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The X-Ray Luminosity--Mass Relation for Local Clusters of Galaxies | | R. Stanek
; A.E. Evrard
; H. B{" o}hringer
; P. Schuecker
; B. Nord
; | | Date: |
15 Feb 2006 | | Abstract: | We investigate the relationship between soft xray luminosity and mass for low redshift clusters of galaxies by comparing observed number counts to expectations of $Lambda$CDM cosmologies. We use a three-parameter model for the conditional probability of luminosity given mass and epoch, described as a log-normal distribution of fixed width centered on a power-law scaling relation, $L spropto M^p
hoc^s(z)$. We use an ensemble of simulated clusters to argue that the observed, intrinsic variance in the temperature--luminosity relation is directly indicative of mass--luminosity variance, and derive $sigm se 0.43 pm 0.06$ from HIFLUGCS data. Adding this to the likelihood analysis results in best-fit estimates $p se 1.59 pm 0.05$, $lnlf se 1.34 pm 0.09$, and $sigm se 0.37 pm 0.05$ for self-similar redshift evolution in a concordance ($Omega_m se 0.3$, $Omega_Lambda se 0.7$, $sigma_8 se0.9$) universe. We show that the present-epoch intercept is very sensitive to power spectrum normalization, $lnlf spropto sigate^{-4}$, and the slope is weakly sensitive to the matter density, $p spropto Omega_m^{1/2}$. The intercept derived here is dimmer by a factor $2$, and slope slightly steeper, than the L-M relation published using hydrostatic mass estimates of the HIFLUGCS sample. We show that this discrepancy is largely due to Malmquist bias of the xray flux-limited sample. Accounting for this effect, we find good agreement. The implication that hydrostatic mass estimates are accurate to within $ssim 15\%$ stresses the need for independent calibration of the local L-M relation via weak gravitational lensing. | | Source: | arXiv, astro-ph/0602324 | | Services: | Forum | Review | PDF | Favorites | |
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