Accretion disks; Active galactic nuclei; Changing-look AGN; MWL variability and spectra; Quasars; Seyfert galaxies; Supermassive binary black holes; Accretion discs; Black holes; Changing-look active galactic nucleus; Multiwavelength; Multiwavelength variability and spectrum; Quasar; Spectra's; Supermassive binary black hole; Aerospace Engineering; Astronomy and Astrophysics; Geophysics; Atmospheric Science; Space and Planetary Science; Earth and Planetary Sciences (all)
Abstract :
[en] The extremes of Active Galactic Nuclei (AGN) variability offer valuable new insights into the drivers and physics of AGN. We discuss some of the most extreme cases of AGN variability; the highest amplitudes, deep minima states, extreme spectral states, Seyfert-type changes, and semi-periodic signals, including new X-ray observations. The properties of changing-look (CL) AGN are briefly reviewed and a classification scheme is proposed which encompasses the variety of CL phenomena; distinguishing slow and fast events, repeat events, and frozen-look AGN which do not show any emission-line response. Long-term light curves that are densely covered over multiple years, along with follow-up spectroscopy, are utilized to gain insight into the underlying variability mechanisms including accretion disk and broad-line region physics. Remarkable differences are seen, for instance, in the optical spectral response to extreme outbursts, implying distinct intrinsic variability mechanisms. Furthermore, we discuss methods for distinguishing between CL AGN and CL look-alike events (tidal disruption events or supernovae in dense media). Finally, semi-periodic light curve variability is addressed and the latest multiwavelength (MWL) light curve of the binary supermassive black hole (SMBH) candidate OJ 287 from the MOMO project is presented. Recent results from that project have clearly established the need for new binary SMBH modelling matching the tight new constraints from observations, including the measurement of a low (primary) SMBH mass of (Formula presented) M⊙ which also implies that OJ 287 is no longer in the regime of near-future pulsar timing arrays.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Komossa, S.; Max-Planck-Institut für Radioastronomie, Bonn, Germany
Grupe, D.; Department of Physics, Geology, and Engineering Technology, Northern Kentucky University, United States
Marziani, P.; National Institute for Astrophysics (INAF), Astronomical Observatory of Padua, Italy
Popović, L.Č.; University of Belgrade - Faculty of Mathematics, Department of Astronomy, Belgrade, Serbia ; Astronomical Observatory, Belgrade, Serbia
Marčeta-Mandić, S.; University of Belgrade - Faculty of Mathematics, Department of Astronomy, Belgrade, Serbia ; Astronomical Observatory, Belgrade, Serbia
Bon, E.; Astronomical Observatory, Belgrade, Serbia
Ilić, D.; University of Belgrade - Faculty of Mathematics, Department of Astronomy, Belgrade, Serbia ; Hamburger Sternwarte, Universität Hamburg, Hamburg, Germany
Kovačević, A.B.; University of Belgrade - Faculty of Mathematics, Department of Astronomy, Belgrade, Serbia
Kraus, A.; Max-Planck-Institut für Radioastronomie, Bonn, Germany
Haiman, Z.; Department of Astronomy, Columbia University, New York, United States ; Department of Physics, Columbia University, New York, United States
Petrecca, V.; Dipartimento di Fisica ”Ettore Pancini”, Napoli, Italy ; INAF - Osservatorio Astronomico di Capodimonte, Napoli, Italy
De Cicco, D.; Dipartimento di Fisica ”Ettore Pancini”, Napoli, Italy ; INAF - Osservatorio Astronomico di Capodimonte, Napoli, Italy ; Millennium Institute of Astrophysics, Santiago, Chile
Dimitrijević, M.S.; Astronomical Observatory, Belgrade, Serbia
Srećković, V.A.; Institute of Physics, University of Belgrade, Belgrade, Serbia
Kovačević Dojčinović, J.; Astronomical Observatory, Belgrade, Serbia
Pannikkote, M.; Physics Department, Tor Vergata University of Rome, Rome, Italy
Bon, N.; Astronomical Observatory, Belgrade, Serbia
Gupta, Kriti Kamal ; Université de Liège - ULiège > Unités de recherche interfacultaires > Space sciences, Technologies and Astrophysics Research (STAR) ; Sterrenkundig Observatorium, Universiteit Gent, Gent, Belgium
Iacob, F.; West University of Timisoara, Timis, Romania
AvH - Alexander von Humboldt-Stiftung University of Belgrade Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja Chinese Academy of Sciences
Funding text :
This article is part of a special issue entitled: \u2019Astrophys. Spect. and Data\u2019 published in Advances in Space Research.We would like to thank the Swift team for carrying out the observations we proposed. In addition to our own data, we have also used the Swift archive athttps://swift.gsfc.nasa.gov/archive/.We would like to thank all participants of the \u201CVI. Conference on Active Galactic Nuclei & Gravitational Lensing\u201D (Serbia, June 2024) for enlightening discussions. S.K. and Z.H. would also like to thank the participants of the conference on \u201CMulti-messenger observations of supermassive black hole binaries\u201D which was supported by the Lorentz Center (Leiden, June 2024) for very stimulating discussions. We would like to thank our referee for very useful comments. S.K. would like to thank R. Antonucci, D. Hutsem\u00E9kers, F. Marin, and M. Ochmann for very useful discussions. E.B., N.B., D.I., A.B.K, J.K.D., S.M.M., and L.\u010C.P. acknowledge funding provided by the University of Belgrade\u2014Faculty of Mathematics (contract 451\u201303-66/2024\u201303/200104) and/or Astronomical Observatory Belgrade (contract 451\u201303-66/2024\u201303/200002), through grants by the Ministry of Education, Science, and Technological Development of the Republic of Serbia. D.I. acknowledges the support of the Alexander von Humboldt Foundation. A.B.K. and L.\u010C.P. thank the support by the Chinese Academy of Sciences President\u2019s International Fellowship Initiative (PIFI) for visiting scientists. V.P. and D.D. acknowledge the financial contribution from PRIN-MIUR 2022 and from the Timedomes grant within the \u201CINAF 2023 Finanziamento della Ricerca Fondamentale\u201D. D.D. also acknowledges PON R&I 2021, CUP E65F21002880003. Z.H. acknowledges support by NSF grant AST-2006176 and NASA grants 80NSSC22K0822 and 80NSSC24K0440. K.K.G. acknowledges the Belgian Federal Science Policy Office (BELSPO) for the provision of financial support in the framework of the PRODEX Programme of the European Space Agency (ESA). This work is partly based on data obtained with the 100m telescope of the Max-Planck-Institut f\u00FCr Radioastronomie at Effelsberg. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester (Evans et al., 2007). This work has made use of public Fermi-LAT data (Abdollahi et al., 2023). This research has made use of the XRT Data Analysis Software (XRTDAS) developed under the responsibility of the ASI Science Data Center (ASDC), Italy. This work has also made use of the NASA Astrophysics Data System Abstract Service (ADS), and the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.We would like to thank the Swift team for carrying out the observations we proposed. In addition to our own data, we have also used the Swift archive at https://swift.gsfc.nasa.gov/archive/. We would like to thank all participants of the \u201CVI. Conference on Active Galactic Nuclei & Gravitational Lensing\u201D (Serbia, June 2024) for enlightening discussions. S.K. and Z.H. would also like to thank the participants of the conference on \u201CMulti-messenger observations of supermassive black hole binaries\u201D which was supported by the Lorentz Center (Leiden, June 2024) for very stimulating discussions. We would like to thank our referee for very useful comments. S.K. would like to thank R. Antonucci, D. Hutsem\u00E9kers, F. Marin, and M. Ochmann for very useful discussions. E.B., N.B., D.I., A.B.K, J.K.D., S.M.M., and L.\u010C.P. acknowledge funding provided by the University of Belgrade\u2014Faculty of Mathematics (contract 451\u201303-66/2024\u201303/200104) and/or Astronomical Observatory Belgrade (contract 451\u201303-66/2024\u201303/200002), through grants by the Ministry of Education, Science, and Technological Development of the Republic of Serbia. D.I. acknowledges the support of the Alexander von Humboldt Foundation. A.B.K. and L.\u010C.P. thank the support by the Chinese Academy of Sciences President\u2019s International Fellowship Initiative (PIFI) for visiting scientists. V.P. and D.D. acknowledge the financial contribution from PRIN-MIUR 2022 and from the Timedomes grant within the \u201CINAF 2023 Finanziamento della Ricerca Fondamentale\u201D. D.D. also acknowledges PON R&I 2021, CUP E65F21002880003. Z.H. acknowledges support by NSF grant AST-2006176 and NASA grants 80NSSC22K0822 and 80NSSC24K0440. K.K.G. acknowledges the Belgian Federal Science Policy Office (BELSPO) for the provision of financial support in the framework of the PRODEX Programme of the European Space Agency (ESA). This work is partly based on data obtained with the 100 m telescope of the Max-Planck-Institut f\u00FCr Radioastronomie at Effelsberg. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester ( Evans et al., 2007 ). This work has made use of public Fermi-LAT data ( Abdollahi et al., 2023 ). This research has made use of the XRT Data Analysis Software (XRTDAS) developed under the responsibility of the ASI Science Data Center (ASDC), Italy. This work has also made use of the NASA Astrophysics Data System Abstract Service (ADS), and the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
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