An improved pressure profile for fitting Sunyaev-Zel'dovich data from Galaxy Clusters
Tony Mroczkowski (Columbia University) , Daisuke Nagai (Caltech), Amber Miller (Columbia), Max Bonamente (MSFC), John E. Carlstrom (U. Chicago), Christopher Greer (U. Chicago), David Hawkins (Caltech-OVRO), Ryan Hennessy (U.Chicago), Marshall Joy (MSFC), James W. Lamb (Caltech-OVRO), Erik M. Leitch (Caltech/JPL), Michael Loh (U.Chicago), Ben Maughan (Bristol, SAO, Chandra Fellow), Stephen Muchovej (Columbia University), Clem Pryke (U.Chicago), Ben Reddall (Caltech-OVRO), Matthew Sharp (U.Chicago), and David Woody (Caltech-OVRO)
We demonstrate the utility of a new model, recently shown to be a robust, self-similar pressure profile, for fitting the current and future generations of Sunyaev-Zel'dovich effect (SZE) observations of galaxy clusters. It has been shown that traditional isothermal -model cannot describe the cluster gas out to the virial, even when the cluster core is excluded. The gas density profile begins to steepen and isothermality is a poor assumption at large radii. When jointly fitting Chandra X-ray and SZ cluster data, the higher signal-to-noise X-ray data drive model shape parameters. For SZE observations of cluster pressure profiles, which are steeper than cluster density profiles due to the decrease in temperature with radius, departures from the isothermal -model are compounded. The isothermal -profile systematically overpredicts the integrated SZ decrement, Yint, which scales as SZ flux and is sensitive to the integrated gas pressure, by
. The need for a model that can describe a cluster's pressure profile at all observable radii has become crucial to the study of the SZE from clusters. Therefore, a new pressure profile, which is not constrained by the X-ray derived density model shape parameters, has been tested. We find this model provides an unbiased estimate of Yint, and, when combined with X-ray image data through the ideal gas law, yields a reasonably-accurate electron temperature profile without relying on X-ray spectroscopic information. In addition to yielding more accurate relationships between cluster observables and physical cluster properties, this model could prove to be a useful tool in helping to constrain the temperatures of high redshift clusters.