Spitzer Space Telescope - General Observer Proposal #60139 Leveraging Spitzer's Legacy: Quasars and Feedback at High Redshift Principal Investigator: Gordon Richards Institution: Drexel University Technical Contact: Gordon Richards, Drexel University Co-Investigators: Scott Anderson, University of Washington Franz Bauer, Columbia Rajesh Deo, Drexel University Xiaohui Fan, University of Arizona Sarah Gallagher, University of Western Ontario Adam Myers, University of Illinois Michael Strauss, Princeton University Nadia Zakamska, Institute for Advanced Study Science Category: AGN/quasars/radio galaxies Observing Modes: IRAC Post-Cryo Mapping Hours Approved: 48.5 Abstract: Recent research efforts to understand the evolution of galaxies and quasars are beginning to form a consistent picture. Galaxies and their supermassive black holes grow through mergers, but with decreasing characteristic mass scales over time. Much less, however, is known about the evolution of galaxies at high redshifts and the role played by energy injection from the onset of active black hole growth. Understanding these events requires investigating a statistically significant number of high-redshift quasars and crossing the L* boundary in luminosity. To construct an appropriate data set requires both relatively wide-areas (to find these rare objects) and moderate-depth imaging (to probe below L* in luminosity). Unfortunately, existing optical and MIR surveys fail to meet both of these requirements. Furthermore, both optical and MIR quasar selection are blindest at the most crucial redshifts. Here we propose to address these gaps with targeted IRAC observations of a few hundred high-redshift quasars from the Sloan Digital Sky Survey. Such a sample will enable the construction of a proper training set for the discovery of 2.5