Статья

1ES 1927+654: An AGN Caught Changing Look on a Timescale of Months

Benny TrakhtenbrotSchool of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel; [email protected]Iair ArcaviSchool of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel; [email protected]Chelsea L. MacLeodCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138-1516, USAClaudio RicciKavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People’s Republic of ChinaErin KaraAstrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USAM. L. GrahamDepartment of Astronomy, University of Washington, Box 351580, U.W., Seattle, WA 98195-1580, USADaniel SternJet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, MS 169-224, Pasadena, CA 91109, USAFiona A. HarrisonCahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, USAJamison BurkeDepartment of Physics, University of California, Santa Barbara, CA 93106-9530, USADaichi HiramatsuDepartment of Physics, University of California, Santa Barbara, CA 93106-9530, USAGriffin HosseinzadehCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138-1516, USAD. A. HowellDepartment of Physics, University of California, Santa Barbara, CA 93106-9530, USAStephen SmarttAstrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN, UKArmin RestDepartment of Physics & Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USAJose L. PrietoMillennium Institute of Astrophysics, Santiago, ChileB. J. ShappeeInstitute for Astronomy, University of Hawai’i, 2680 Woodlawn Drive, Honolulu, HI 96822, USAT. W. S. HoloienThe Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101, USAD. BersierAstrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UKA. V. FilippenkoDepartment of Astronomy, University of California, Berkeley, CA 94720-3411, USAThomas G. BrinkDepartment of Astronomy, University of California, Berkeley, CA 94720-3411, USAWeiKang ZhengDepartment of Astronomy, University of California, Berkeley, CA 94720-3411, USARuancun LiKavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People’s Republic of ChinaRonald A. RemillardMIT Kavli Institute for Astrophysics and Space Research, 70 Vassar Street, Cambridge, MA 02139, USAMichael LoewensteinAstrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA

2019en

ABI

Аннотация

Abstract We study the sudden optical and ultraviolet (UV) brightening of 1ES 1927+654, which until now was known as a narrow-line active galactic nucleus (AGN). 1ES 1927+654 was part of the small and peculiar class of “true Type-2” AGNs that lack broad emission lines and line-of-sight obscuration. Our high-cadence spectroscopic monitoring captures the appearance of a blue, featureless continuum, followed several weeks later by the appearance of broad Balmer emission lines. This timescale is generally consistent with the expected light travel time between the central engine and the broadline emission region in (persistent) broadline AGN. Hubble Space Telescope spectroscopy reveals no evidence for broad UV emission lines (e.g., C iv λ 1549, C iii ] λ 1909, Mg ii λ 2798), probably owing to dust in the broadline emission region. To the best of our knowledge, this is the first case where the lag between the change in continuum and in broadline emission of a “changing look” AGN has been temporally resolved. The nature and timescales of the photometric and spectral evolution disfavor both a change in line-of-sight obscuration and a change of the overall rate of gas inflow as driving the drastic spectral transformations seen in this AGN. Although the peak luminosity and timescales are consistent with those of tidal disruption events seen in inactive galaxies, the spectral properties are not. The X-ray emission displays a markedly different behavior, with frequent flares on timescales of hours to days, and will be presented in a companion publication.

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Идентификаторы

DOI: 10.3847/1538-4357/ab39e4

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Цитирований: 2Использованных источников: 0

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