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The Time Domain Spectroscopic Survey: Changing-look Quasar Candidates from Multi-epoch Spectroscopy in SDSS-IV

Green, Paul J. and Pulgarin-Duque, Lina and Anderson, Scott F. and MacLeod, Chelsea L. and Eracleous, Michael and Ruan, John J. and Runnoe, Jessie and Graham, Matthew and Roulston, Benjamin R. and Schneider, Donald P. and Ahlf, Austin and Bizyaev, Dmitry and Brownstein, Joel R. and del Casal, Sonia Joesephine and Dodd, Sierra A. and Hoover, Daniel and Matt, Cayenne and Merloni, Andrea and Pan, Kaike and Ramirez, Arnulfo and Ridder, Margaret (2022) The Time Domain Spectroscopic Survey: Changing-look Quasar Candidates from Multi-epoch Spectroscopy in SDSS-IV. Astrophysical Journal, 933 (2). Art. No. 180. ISSN 0004-637X. doi:10.3847/1538-4357/ac743f. https://resolver.caltech.edu/CaltechAUTHORS:20220722-769194000

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Abstract

Active galactic nuclei (AGN) can vary significantly in their rest-frame optical/UV continuum emission, and with strong associated changes in broad line emission, on much shorter timescales than predicted by standard models of accretion disks around supermassive black holes. Most such changing-look or changing-state AGN—and at higher luminosities, changing-look quasars (CLQs)—have been found via spectroscopic follow-up of known quasars showing strong photometric variability. The Time Domain Spectroscopic Survey of the Sloan Digital Sky Survey IV (SDSS-IV) includes repeat spectroscopy of large numbers of previously known quasars, many selected irrespective of photometric variability, and with spectral epochs separated by months to decades. Our visual examination of these repeat spectra for strong broad line variability yielded 61 newly discovered CLQ candidates. We quantitatively compare spectral epochs to measure changes in continuum and Hβ broad line emission, finding 19 CLQs, of which 15 are newly recognized. The parent sample includes only broad line quasars, so our study tends to find objects that have dimmed, i.e., turn-off CLQs. However, we nevertheless find four turn-on CLQs that meet our criteria, albeit with broad lines in both dim and bright states. We study the response of Hβ and Mg ii emission lines to continuum changes. The Eddington ratios of CLQs are low, and/or their Hβ broad line width is large relative to the overall quasar population. Repeat quasar spectroscopy in the upcoming SDSS-V black hole Mapper program will reveal significant numbers of CLQs, enhancing our understanding of the frequency and duty cycle of such strong variability, and the physics and dynamics of the phenomenon.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/ac743fDOIArticle
https://arxiv.org/abs/2201.09123arXivDiscussion Paper
ORCID:
AuthorORCID
Green, Paul J.0000-0002-8179-9445
MacLeod, Chelsea L.0000-0003-3422-2202
Eracleous, Michael0000-0002-3719-940X
Ruan, John J.0000-0001-8665-5523
Runnoe, Jessie0000-0001-8557-2822
Graham, Matthew0000-0002-3168-0139
Roulston, Benjamin R.0000-0002-9453-7735
Schneider, Donald P.0000-0001-7240-7449
Bizyaev, Dmitry0000-0002-3601-133X
Brownstein, Joel R.0000-0002-8725-1069
Dodd, Sierra A.0000-0002-3696-8035
Pan, Kaike0000-0002-2835-2556
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2022 January 13; revised 2022 April 25; accepted 2022 May 23; published 2022 July 13. Many thanks to Qian Yang for comments and suggestions. S.F.A., P.J.G., C.L.M, B.R., and J.J.R. are supported by the National Science Foundation under grant Nos. AST- 1715121, and AST-1715763. C.L.M. and Q.Y. were partially supported for spectroscopic observations and analysis by the National Aeronautics and Space Administration through Chandra Award Nos. GO8-19089X and GO9-20086X, issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract No. NAS8-03060. Photometric light curves used herein are based on observations obtained with the Samuel Oschin 48 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and the Lawrence Berkeley National Laboratory. Operations are conducted by COO, IPAC, and UW. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High Performance Computing at the University of Utah. The SDSS website is www.sdss.org. SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, Center for Astrophysics ∣ Harvard & Smithsonian, the Chilean Participation Group, the French Participation Group, Instituto de Astrofísica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo, the Korean Participation Group, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Max-Planck-Institut für Astrophysik (MPA Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), National Astronomical Observatories of China, New Mexico State University, New York University, University of Notre Dame, Observatário Nacional/MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autónoma de México, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University. The authors acknowledge the use of the Catalog Archive Server Jobs System (CasJobs) service at http://casjobs.sdss.org/CasJobs, developed by the JHU/SDSS team. This work uses data obtained with the 1.2 m Samuel Oschin Telescope at Palomar Observatory as part of the Palomar Transient Factory project, a scientific collaboration among the California Institute of Technology, Columbia University, Las Cumbres Observatory, the Lawrence Berkeley National Laboratory, the National Energy Research Scientific Computing Center, the University of Oxford, and the Weizmann Institute of Science. The Zwicky Transient Facility is supported by the NSF under grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. The Pan-STARRS1 Surveys (PS1) have been made possible through contributions of the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation under grant No. AST-1238877, the University of Maryland, and Eotvos Lorand University (ELTE). This work made use of data products from the Catalina Sky Survey. The CSS survey is funded by the National Aeronautics and Space Administration under grant No. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program. The CRTS survey is supported by the U.S. National Science Foundation under grant Nos. AST-0909182 and AST-1313422. Facilities: Sloan - Sloan Digital Sky Survey Telescope, ING:Herschel - , Magellan:Baade (LDSS2 imaging spectrograph - , Boller & Chivens spectrograph) - , MMT (Blue Channel spectrograph - , BinoSpec) - , PS1 - , PO:1.2 m - , SO:Schmidt - , SO:1.5 m - , SO:1m - . Software: Astropy (Astropy Collaboration et al. 2013, 2018), Matplotlib (Hunter 2007), NumPy (Harris et al. 2020), SciPy (Virtanen et al. 2020), TOPCAT (Taylor 2005).
Group:Zwicky Transient Facility, Palomar Transient Factory
Funders:
Funding AgencyGrant Number
NSFAST-1715121
NSFAST-1715763
NASAGO8-19089X
NASAGO9-20086X
NASANAS8-03060
NSFAST-1440341
ZTF partner institutionsUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Participating InstitutionsUNSPECIFIED
Pan-STARRS Project OfficeUNSPECIFIED
NASANNX08AR22G
NSFAST-1238877
University of MarylandUNSPECIFIED
Eotvos Lorand University (ELTE)UNSPECIFIED
NASANNG05GF22G
NSFAST-0909182
NSFAST-1313422
Subject Keywords:Accretion; Quasars; Active galactic nuclei; Variable radiation sources; Catalogs
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Accretion (14); Quasars (1319); Active galactic nuclei (16); Variable radiation sources (1759); Catalogs (205)
DOI:10.3847/1538-4357/ac743f
Record Number:CaltechAUTHORS:20220722-769194000
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20220722-769194000
Official Citation:Paul J. Green et al 2022 ApJ 933 180
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115787
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:26 Jul 2022 19:12
Last Modified:26 Jul 2022 19:12

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