Surface Brightness Fluctuations in Two SPT Clusters: a Pilot Study

Studies of surface brightness fluctuations in the intracluster medium (ICM)present an indirect probe of turbulent properties such as the turbulentvelocities, injection scales, and the slope of the power spectrum offluctuations towards smaller scales. With the advancement of Sunyaev-Zel'dovich(SZ) studies and surveys relative to X-ray observations, we seek to investigatesurface brightness fluctuations in a sample of SPT-SZ clusters which also havearchival XMM-Newton data. Here we present a pilot study of two typicalclusters in that sample: SPT-CLJ0232-4421 and SPT-CLJ0638-5358. We inferinjection scales larger than 500 kpc in both clusters and Mach numbers ≈0.5 in SPT-CLJ0232-4421 and Mach numbers ≈ 0.6 - 1.6 inSPT-CLJ0638-5358, which has a known shock. We find hydrostatic bias values forM_500 less than 0.2 for SPT-CLJ0232-4421 and less than 0.1 forSPT-CLJ0638-5358. These results show the importance to assess its quantitativevalues via a detailed multiwavelength approach and suggest that the drivers ofturbulence may occur at quite larger scales.