Cooke, Kevin C.Kirkpatrick, AllisonEstrada, MichaelMessias, HugoPeca, AlessandroCappelluti, NicoAnanna, Tonima TasnimBrewster, JasonGlikman, EilatLaMassa, StephanieLeung, T. K. DaisyTrump, Jonathan R.Turner, Tracey JaneUrry, C. Megan2021-01-262021-01-262020-11-06Kevin C. Cooke et al (2020), Dying of the Light: An X-Ray Fading Cold Quasar at z ~ 0.405, The Astrophysical Journal, Volume 903, Number 2, https://iopscience.iop.org/article/10.3847/1538-4357/abb94ahttp://hdl.handle.net/11603/20620Cold quasars are a rare subpopulation observed to host unobscured, X-ray luminous active galactic nuclei (AGN) while also retaining a cold gas supply fueling high star formation rates. These objects are interpreted as AGN early in their evolution. We present new SOFIA HAWC+ far-infrared observations, far-ultraviolet to far-infrared (FUV–FIR) photometry, and optical spectroscopy to characterize the accretion and star formation behavior in a cold quasar at z ~ 0.405 (CQ 4479). CQ 4479 is a starburst galaxy with a predominantly young stellar population and a high gas mass fraction of ~50%–70%. The AGN component has yet to become the dominant component of the FIR emission. We also find AGN bolometric luminosity that varies as a function of observation method and AGN region probed. Finally, we identify a candidate outflow feature corroborating the hypothesis that cold quasars have energetic feedback. This object presents an intriguing look into the early stages of AGN feedback and probes the rare phase where an AGN and cold gaseous component coexist.10 pagesen-USThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.© 2020. The American Astronomical Society. All rights reserved.active galactic nucleiinfrared excess galaxiesgalaxy evolutiongalaxy quenchingx-ray quasarsText