Quasar hosts: Growing up with monstrous middles

Summary

The Hubble Space Telescope has shown us the homes of nearby quasars in revealing detail, and has dealt us surprising answers to some of our long-standing questions about quasar host galaxy morphology. However, like all cutting-edge instruments, HST has taught us that the very questions we were asking were not necessarily the most interesting ones. Exploring the latter will require a combination of ground- and space-based work over the remaining lifetime of HST, and beyond. Such studies promise to give us insight into the formation and evolution of galaxies like our own over the whole history of the Universe.

Introduction

HST and quasar host galaxy studies have grown up together over the past 30 years. Indeed, “the imaging of low-redshift quasars at high angular resolution (∼0″.1) is one of the principal scientific goals for which the Hubble Space Telescope was designed” (Bahcall, Kirhakos, & Schneider 1994). The nice demonstration by Kristian (1973) that nearby quasars are, in fact, surrounded by “fuzz” in deep 200-inch photographs provided timely input for the design of HST and its instruments, the specifications for which were outlined by the Large Space Telescope Science Working Group in 1974 (HST website). While HST has changed the way we look at quasar hosts, the ultimate goal of our studies has not changed over the decades. Then, as now, we strive to understand the roles played by quasars in galaxy evolution.