Schedule Mar 15, 2011
The APEX-SZ Experiment and SZ/X-ray Joint Analysis of the Intra-Cluster Medium
Kaustuv Basu (Univ. Bonn)

The APEX-SZ instrument is a 300-element bolometer camera that operated at 5100 meter elevation in Chile during 2007-2010, observing X-ray selected galaxy clusters through the Sunyaev-Zel'dovich (SZ) effect at 150 GHz. It recently completed its data acquisition phase with successful detection of over 30 clusters, encompassing a wide mass and redshift range. In this talk I will present a brief overview of the experiment, including the first set of published results and some on-going works, and describe in detail our attempt to model the physical properties of the Intra-Cluster Medium (ICM) through a joint SZ/X-ray analysis. High-resolution SZ imaging with wide-field bolometer cameras have only recently made it possible to probe the ICM physical properties at different scales complimenting the X-ray spectral analysis, and APEX-SZ has set a benchmark in this field by successfully combining SZ and X-ray imaging data to de-project the ICM density and temperature profiles to beyond r_500. I describe our non-parametric modeling technique and how it can demonstrate the existence of cluster "entropy floor" and temperature drop in the outskirts without the use of X-ray spectroscopy. Our early analysis is now being extended to a wider sample, and I will present the preliminary results for a stacked temperature profile that reach out to the cluster virial radius. I will also demonstrate how our non-parametric modeling of the ICM pressure compares with the X-ray predicted "universal pressure profile".

Basu, K., Zhang, Y.-Y. et al. 2010, A&A, 519, 29
Nord, M., Basu, K. et al. 2009, A&A. 506, 623

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