Year: 2016
Type: article
Abstract: ABSTRACT The uncertain origin of the recently discovered “changing-look” quasar phenomenon—in which a luminous quasar dims significantly to a quiescent state in repeat spectroscopy over ∼10-year timescales—may present unexpected challenges to our understanding of quasar accretion. To better understand this phenomenon, we take a first step toward building a sample of changing-look quasars with a systematic but simple archival search for these objects in the Sloan Digital Sky Survey Data Release 12. By leveraging the >10-year baselines for objects with repeat spectroscopy, we uncover two new changing-look quasars and a third discovered previously. Decomposition of the multiepoch spectra and analysis of the broad emission lines suggest that the quasar accretion disk emission dims because of rapidly decreasing accretion rates (by factors of ≳2.5), while disfavoring changes in intrinsic dust extinction for the two objects where these analyses are possible. Broad emission line energetics also support intrinsic dimming of quasar emission as the origin for this phenomenon rather than transient tidal disruption events or supernovae. Although our search criteria included quasars at all redshifts and transitions from either quasar-like to galaxy-like states or the reverse, all of the clear cases of changing-look quasars discovered were at relatively low redshift ( ) and only exhibit quasar-like to galaxy-like transitions.
Source: The Astrophysical Journal
Authors: John J. Ruan, Scott F. Anderson, Sabrina L. Cales, Michael Eracleous, Paul J. Green, Eric Morganson, Jessie C. Runnoe, Yue Shen, Tessa D. Wilkinson, Michael R. Blanton, Tom Dwelly, Antonis Georgakakis, Jenny E. Greene, Stephanie M. LaMassa, Andrea Merloni, Donald P. Schneider
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, Alfred P. Sloan Foundation, Yale University, Vanderbilt University, Princeton University, Ohio State University, Harvard University, University of Washington, Johns Hopkins University, Carnegie Mellon University, University of Portsmouth, New Mexico State University, York University, Office of Science, College of Engineering, Michigan State University, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory
OpenAlex ID: W2395443874