MUSTANG HIGH ANGULAR RESOLUTION SUNYAEV-ZEL'DOVICH EFFECT IMAGING OF SUBSTRUCTURE IN FOUR GALAXY CLUSTERS

Abstract

We present 10" to 18" images of four massive clusters of galaxies through the\nSunyaev-Zel'dovich Effect (SZE). These measurements, made at 90~GHz with the\nMUSTANG receiver on the Green Bank Telescope (GBT), reveal pressure\nsub-structure to the intra-cluster medium (ICM) in three of the four systems.\nWe identify the likely presence of a previously unknown weak shock-front in\nMACS0744+3927. By fitting the Rankine-Hugoniot density jump conditions in a\ncomplementary SZE/X-ray analysis, we infer a Mach number of M =\n1.2^{+0.2}_{-0.2} and a shock-velocity of 1827^{+267}_{-195}~km/s. In\nRXJ1347-1145, we present a new reduction of previously reported data and\nconfirm the presence of a south-east SZE enhancement with a significance of\n13.9 sigma when smoothed to 18" resolution. This too is likely caused by\nshock-heated gas produced in a recent merger. In our highest redshift system,\nCL1226+3332, we detect sub-structure at a peak significance of 4.6 sigma in the\nform of a ridge oriented orthogonally to the vector connecting the main mass\npeak and a sub-clump revealed by weak lensing. We also conclude that the gas\ndistribution is elongated in a south-west direction, consistent with a\npreviously proposed merger scenario. The SZE image of the cool core cluster\nAbell 1835 is, in contrast, consistent with azimuthally symmetric signal only.\nThis pilot study demonstrates the potential of high-resolution SZE images to\ncomplement X-ray data and probe the dynamics of galaxy clusters\n