SZE scaling relations from a `working’ model of galaxy clusters

Subha Majumdar

June 03, 2010

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Abstract: We build a simple, working model, of the gas density, temperature (and hence pressure) profiles of galaxy clusters. The basic model has no `free’ parameters; however, by construction, the model satisfies the observed XRay mass-temperature relation and mimics the temperature profiles seen in recent high resolution XRay observations. The gas is assumed to be in hydrostatic equilibrium along with a component of non-thermal pressure taken from simulations. We use this model to calculate Sunyaev-Zel’dovich (SZE) properties and compare with observations. We find nice agreement with the gas pressure profile found by Arnaud et al (2009) and SZE scaling relations observed by Bonamente et al (2008). We also find gas fraction within r500 increasing with the underlying mas M500, similar to observations. Going in reverse, we can constrain the mass-temperature relation of galaxy clusters by finding the best fitting cluster model to the Bonamente SZE scaling data. These, then, turn out to be in nice agreement with the observed XRay results. The consistency between the global properties of clusters detected in X-Ray‰Ûªs and in SZE shows that we are looking at a common population of clusters as a whole, and there is no deficit of SZE flux relative to expectations from X-Ray scaling properties. Moreover, being analytical in nature, our model can be easily used for MCMC runs. Finally, we take a look at the implications for M200 scaling relations and SZ power spectrum.