Dr. Ohad Shemmer receives $193k Chandra Grant for project titled "Chandra's Crucial Role in Identifying a Robust and Practical Accretion-Rate Indicator for Quasars."

Abstract: "Understanding the rapid growth of supermassive black holes and the assembly of their host galaxies is severely limited by the lack of reliable estimates of black-hole mass and accretion rate in distant quasars. We propose Chandra observations of 54 luminous, high-redshift quasars to boost our ability to identify the most reliable and practical Eddington-ratio indicator. In conjunction with archival data, we will investigate diagnostics of quasar accretion power in the X-ray and UV-optical spectral bands of a carefully selected sample of ~80 sources. We will "stress test'' these diagnostics, relying critically on the X-ray observable properties, and deliver a prescription for the most robust Eddington-ratio estimate that can be utilized economically at the highest accessible redshifts."