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Burke CJ, Shen Y, Blaes O, Gammie CF, Horne K, Jiang YF, Liu X, McHardy IM, Morgan CW, Scaringi S, Yang Q. A characteristic optical variability time scale in astrophysical accretion disks. Science 2021; 373:789-792. [PMID: 34385395 DOI: 10.1126/science.abg9933] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 06/11/2021] [Indexed: 12/30/2022]
Abstract
Accretion disks around supermassive black holes in active galactic nuclei produce continuum radiation at ultraviolet and optical wavelengths. Physical processes in the accretion flow lead to stochastic variability of this emission on a wide range of time scales. We measured the optical continuum variability observed in 67 active galactic nuclei and the characteristic time scale at which the variability power spectrum flattens. We found a correlation between this time scale and the black hole mass extending over the entire mass range of supermassive black holes. This time scale is consistent with the expected thermal time scale at the ultraviolet-emitting radius in standard accretion disk theory. Accreting white dwarfs lie close to this correlation, suggesting a common process for all accretion disks.
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Affiliation(s)
- Colin J Burke
- Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,Center for AstroPhysical Surveys, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Yue Shen
- Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. .,National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Omer Blaes
- Department of Physics, University of California, Santa Barbara, CA 93106, USA
| | - Charles F Gammie
- Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,Illinois Center for Advanced Study of the Universe, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Keith Horne
- School of Physics and Astronomy, University of St. Andrews, Fife KY16 9SS, UK
| | - Yan-Fei Jiang
- Center for Computational Astrophysics, Flatiron Institute, New York, NY 10010, USA
| | - Xin Liu
- Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Ian M McHardy
- Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK
| | | | - Simone Scaringi
- Department of Physics, University of Durham, Durham DH1 3LE, UK
| | - Qian Yang
- Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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A Multi-Wavelength View of OJ 287 Activity in 2015–2017: Implications of Spectral Changes on Central-Engine Models and MeV-GeV Emission Mechanism. GALAXIES 2020. [DOI: 10.3390/galaxies8010015] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A diverse range of observational results and peculiar properties across the domains of observation have made OJ 287 one of the best-explored BL Lac objects on the issues of relativistic jets and accretion physics as well as the strong theory of gravity. We here present a brief compilation of observational results from the literature and inferences/insights from the extensive studies but focus on the interpretation of its ∼12-yr quasi-periodic optical outbursts (QPOOs) and high energy emission mechanisms. The QPOOs in one model are attributed to the disk-impact related to dynamics of the binary SMBHs while alternative models attribute it to the geometrical effect related to the precession of a single jet or double jets. We discuss implications of the new spectral features reported during the 2015–2017 multi-wavelength high activity of the source—a break in the NIR-optical spectrum and hardening of the MeV-GeV emission accompanied by a shift in the location of its peak, in the context of the two. The reported NIR-optical break nicely fits the description of a standard accretion disk emission from an SMBH of mass ∼ 10 10 M ⊙ while the time of its first appearance at the end of May, 2013 (MJD 56439) is in close coincidence with the time of impact predicted by the disk-impact binary SMBH model. This spectral and temporal coincidence with the model parameters of the disk-impact binary SMBH model provides independent evidence in favor of the model over the geometrical models which argue for a total central-engine mass in the range of 10 7 - 9 M ⊙ . On the other hand, the MeV-GeV spectral change is naturally reproduced by the inverse Compton scattering of photons from the broad-line region and is consistent with the detection of broad emission lines during the previous cycles of quasi-periodic outbursts. Combining this with previous SED studies suggests that in, OJ 287, the MeV-GeV emission results from external Comptonization.
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Magnetically gated accretion in an accreting 'non-magnetic' white dwarf. Nature 2017; 552:210-213. [PMID: 29239355 DOI: 10.1038/nature24653] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 10/16/2017] [Indexed: 11/08/2022]
Abstract
White dwarfs are often found in binary systems with orbital periods ranging from tens of minutes to hours in which they can accrete gas from their companion stars. In about 15 per cent of these binaries, the magnetic field of the white dwarf is strong enough (at 106 gauss or more) to channel the accreted matter along field lines onto the magnetic poles. The remaining systems are referred to as 'non-magnetic', because until now there has been no evidence that they have a magnetic field that is strong enough to affect the accretion dynamics. Here we report an analysis of archival optical observations of the 'non-magnetic' accreting white dwarf in the binary system MV Lyrae, whose light curve displays quasi-periodic bursts of about 30 minutes duration roughly every 2 hours. The timescale and amplitude of these bursts indicate the presence of an unstable, magnetically regulated accretion mode, which in turn implies the existence of magnetically gated accretion, in which disk material builds up around the magnetospheric boundary (at the co-rotation radius) and then accretes onto the white dwarf, producing bursts powered by the release of gravitational potential energy. We infer a surface magnetic field strength for the white dwarf in MV Lyrae of between 2 × 104 gauss and 1 × 105 gauss, too low to be detectable by other current methods. Our discovery provides a new way of studying the strength and evolution of magnetic fields in accreting white dwarfs and extends the connections between accretion onto white dwarfs, young stellar objects and neutron stars, for which similar magnetically gated accretion cycles have been identified.
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Revet G, Chen SN, Bonito R, Khiar B, Filippov E, Argiroffi C, Higginson DP, Orlando S, Béard J, Blecher M, Borghesi M, Burdonov K, Khaghani D, Naughton K, Pépin H, Portugall O, Riquier R, Rodriguez R, Ryazantsev SN, Yu. Skobelev I, Soloviev A, Willi O, Pikuz S, Ciardi A, Fuchs J. Laboratory unraveling of matter accretion in young stars. SCIENCE ADVANCES 2017; 3:e1700982. [PMID: 29109974 PMCID: PMC5665592 DOI: 10.1126/sciadv.1700982] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 10/05/2017] [Indexed: 06/07/2023]
Abstract
Accretion dynamics in the formation of young stars is still a matter of debate because of limitations in observations and modeling. Through scaled laboratory experiments of collimated plasma accretion onto a solid in the presence of a magnetic field, we open a first window on this phenomenon by tracking, with spatial and temporal resolution, the dynamics of the system and simultaneously measuring multiband emissions. We observe in these experiments that matter, upon impact, is ejected laterally from the solid surface and then refocused by the magnetic field toward the incoming stream. This ejected matter forms a plasma shell that envelops the shocked core, reducing escaped x-ray emission. This finding demonstrates one possible structure reconciling current discrepancies between mass accretion rates derived from x-ray and optical observations, respectively.
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Affiliation(s)
- Guilhem Revet
- Institute of Applied Physics, 46 Ulyanov Street, 603950 Nizhny Novgorod, Russia
- LULI (Laboratoire pour l’Utilisation des Lasers Intenses)–CNRS, École Polytechnique; Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Université Paris-Saclay; Sorbonne Universités, Universite Pierre et Marie Curie (UPMC) Paris 06, F-91128 Palaiseau cedex, France
| | - Sophia N. Chen
- Institute of Applied Physics, 46 Ulyanov Street, 603950 Nizhny Novgorod, Russia
- LULI (Laboratoire pour l’Utilisation des Lasers Intenses)–CNRS, École Polytechnique; Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Université Paris-Saclay; Sorbonne Universités, Universite Pierre et Marie Curie (UPMC) Paris 06, F-91128 Palaiseau cedex, France
| | - Rosaria Bonito
- INAF (Istituto Nazionale di Astrofisica)–Osservatorio Astronomico di Palermo, Palermo, Italy
- Dipartimento di Fisica e Chimica, Università di Palermo, Palermo, Italy
| | - Benjamin Khiar
- Sorbonne Universités, UPMC Paris 06, Observatoire de Paris, PSL (Paris Sciences et Lettre) Research University, CNRS, UMR 8112, LERMA (Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique), F-75005 Paris, France
| | - Evgeny Filippov
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow 115409, Russia
- Joint Institute for High Temperatures, RAS (Russian Academy of Sciences), Moscow 125412, Russia
| | | | - Drew P. Higginson
- LULI (Laboratoire pour l’Utilisation des Lasers Intenses)–CNRS, École Polytechnique; Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Université Paris-Saclay; Sorbonne Universités, Universite Pierre et Marie Curie (UPMC) Paris 06, F-91128 Palaiseau cedex, France
- Lawrence Livermore National Laboratory, Livermore, CA 94551, USA
| | - Salvatore Orlando
- INAF (Istituto Nazionale di Astrofisica)–Osservatorio Astronomico di Palermo, Palermo, Italy
| | - Jérôme Béard
- LNCMI (Laboratoire National des Champs Magnétiques Intenses), UPR 3228, CNRS-UGA-UPS-INSA, Toulouse 31400, France
| | - Marius Blecher
- Institut für Laser- und Plasmaphysik, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | - Marco Borghesi
- Centre for Plasma Physics, Queen’s University of Belfast, Belfast BT7 1NN, UK
| | - Konstantin Burdonov
- Institute of Applied Physics, 46 Ulyanov Street, 603950 Nizhny Novgorod, Russia
| | - Dimitri Khaghani
- GSI (Gesellschaft für Schwerionenforschung) Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
| | - Kealan Naughton
- Centre for Plasma Physics, Queen’s University of Belfast, Belfast BT7 1NN, UK
| | - Henri Pépin
- INRS-EMT (Institut National de la Recherche Scientifique, Énergie, Matériaux et Télécommunication), Varennes, Québec, Canada
| | - Oliver Portugall
- LNCMI (Laboratoire National des Champs Magnétiques Intenses), UPR 3228, CNRS-UGA-UPS-INSA, Toulouse 31400, France
| | - Raphael Riquier
- LULI (Laboratoire pour l’Utilisation des Lasers Intenses)–CNRS, École Polytechnique; Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Université Paris-Saclay; Sorbonne Universités, Universite Pierre et Marie Curie (UPMC) Paris 06, F-91128 Palaiseau cedex, France
- CEA, DAM, DIF (Commissariat à l’Energie Atomique Energie Atomique, Direction des Applications Militaires Île de France), 91297 Arpajon, France
| | - Rafael Rodriguez
- Departamento de Fisica de la Universidad de Las Palmas de Gran Canaria, E-35017 Las Palmas de Gran Canaria, Spain
| | - Sergei N. Ryazantsev
- Joint Institute for High Temperatures, RAS (Russian Academy of Sciences), Moscow 125412, Russia
| | - Igor Yu. Skobelev
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow 115409, Russia
- Joint Institute for High Temperatures, RAS (Russian Academy of Sciences), Moscow 125412, Russia
| | - Alexander Soloviev
- Institute of Applied Physics, 46 Ulyanov Street, 603950 Nizhny Novgorod, Russia
| | - Oswald Willi
- Institut für Laser- und Plasmaphysik, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | - Sergey Pikuz
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow 115409, Russia
- Joint Institute for High Temperatures, RAS (Russian Academy of Sciences), Moscow 125412, Russia
| | - Andrea Ciardi
- Sorbonne Universités, UPMC Paris 06, Observatoire de Paris, PSL (Paris Sciences et Lettre) Research University, CNRS, UMR 8112, LERMA (Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique), F-75005 Paris, France
| | - Julien Fuchs
- Institute of Applied Physics, 46 Ulyanov Street, 603950 Nizhny Novgorod, Russia
- LULI (Laboratoire pour l’Utilisation des Lasers Intenses)–CNRS, École Polytechnique; Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Université Paris-Saclay; Sorbonne Universités, Universite Pierre et Marie Curie (UPMC) Paris 06, F-91128 Palaiseau cedex, France
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