Astronomy Colloquium

  We now believe that every large galaxy hosts a supermassive black hole at its core, with masses ranging from millions to billions of times that of our Sun.  At times, these black holes are actively accreting, causing the nuclei of the galaxies to shine brightly across the electromagnetic spectrum.  However, most quasars have obscuring material along the line of sight that shields the inner nucleus.  This obscuring material is heated, and emits strongly in the mid-infrared.  The Wide-field Infrared Survey Explorer, or WISE, has mapped the entire sky in mid-infrared light with exquisite depth and clarity.  WISE has allowed us to find luminous quasars across the whole sky due to this heated material, more than tripling the number of quasars known.  I will discuss several surprising new insights into quasars that have come out of this work.  In brief, the dominant paradigms do not match our observations, with potentially important implications for the role of quasars in the growth of galaxies.  I will conclude by discussing how these studies will be further enabled by the Euclid and WFIRST satellites.