Revisiting the Baryon Fractions of Galaxy Clusters: A Comparison with WMAP 3-year Results

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dc.creatorMcCarthy, Ian G.
dc.creatorBower, Richard G.
dc.creatorBalogh, Michael L.
dc.date2006-09-12
dc.date2007-03-13
dc.date.accessioned2026-07-07T11:04:10Z
dc.date.available2026-07-07T11:04:10Z
dc.descriptionThe universal baryonic mass fraction (Omega_b/Omega_m) can be sensitively constrained using X-ray observations of galaxy clusters. In this paper, we compare the baryonic mass fraction inferred from measurements of the cosmic microwave background with the gas mass fractions (f_gas) of a large sample of clusters taken from the recent literature. In systems cooler than 4 keV, f_gas declines as the system temperature decreases. However, in higher temperature systems, f_gas(r500) converges to approx. (0.12 +/- 0.02)(h/0.72)^{-1.5}, where the uncertainty reflects the systematic variations between clusters at r500. This is significantly lower than the maximum-likelihood value of the baryon fraction from the recently released WMAP 3-year results. We investigate possible reasons for this discrepancy, including the effects of radiative cooling and non-gravitational heating, and conclude that the most likely solution is that Omega_m is higher than the best-fit WMAP value (we find Omega_m = 0.36^{+0.11}_{-0.08}), but consistent at the 2-sigma level. Degeneracies within the WMAP data require that sigma_8 must also be greater than the maximum likelihood value for consistency between the data sets.
dc.description8 pages, 3 figures, MNRAS accepted
dc.identifierhttps://arxiv.org/abs/astro-ph/0609314
dc.identifierhttp://arxiv.org/abs/astro-ph/0609314
dc.identifierMon.Not.Roy.Astron.Soc.377:1457-1463,2007
dc.identifierdoi:10.1111/j.1365-2966.2007.11733.x
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/188799
dc.subjectAstrophysics
dc.titleRevisiting the Baryon Fractions of Galaxy Clusters: A Comparison with WMAP 3-year Results
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