Princeton University Gravity Group Astrophysics/Cosmology Seminar - NOTE TIME

ABSTRACT: We present new results on ACT-CL J0102-4915 ("El Gordo") based on Hubble ACS imaging and a deep Chandra observation. I will review the strong and weak lensing analyses presented in Zitrin et al (2013) and Jee et al (2013), respectively. These studies directly reveal the bimodal mass distribution of the cluster and provide mass measurements of ~2E15 to ~3E15 solar masses that confirm previous values from X-ray and dynamical studies. I will present a temperature map of the hot X-ray emitting gas on sub-arcminute scales that shows significant variations from a low of 5 keV near the location of the brightest cluster galaxy (BCG) to a high of 25 keV elsewhere. The cold core shows evidence for a cold front, an interface across which the temperature decreases while the density rises, providing further evidence for a major merger in El Gordo. We also examine the locations of merger shocks as traced by radio relics (recently reported by Lindner et al 2013) to search for density and temperature jumps in the hot cluster gas. I will relate the density, temperature and, possibly, abundance structures visible in the Chandra data with our results from gravitational lensing analyses of El Gordo.