A new class of flares from accreting supermassive black holes

Autor: Benny Trakhtenbrot, Mariusz Gromadzki, Iair Arcavi, Erin Kara, S. Bradley Cenko, Nikita Kamraj, A. Hamanowicz, David J. Sand, Mark M. Phillips, Hagai Netzer, Marianne Heida, Ron Remillard, Sandro Tacchella, D. Andrew Howell, Daniel Stern, J. Mejia-Restrepo, Łukasz Wyrzykowski, Curtis McCully, Griffin Hosseinzadeh, Valentina Hallefors, Claudio Ricci, Mislav Baloković, T. R. Diamond, Keith C. Gendreau, Peter G. Jonker, George B. Lansbury, Zaven Arzoumanian, Assaf Horesh, Eric Hsiao
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Active galactic nucleus
010504 meteorology & atmospheric sciences
Electromagnetic spectrum
Astronomy
Astrophysics::High Energy Astrophysical Phenomena
FOS: Physical sciences
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
01 natural sciences
law.invention
law
0103 physical sciences
Astrophysics::Solar and Stellar Astrophysics
Emission spectrum
010303 astronomy & astrophysics
Astrophysics::Galaxy Astrophysics
0105 earth and related environmental sciences
Physics
High Energy Astrophysical Phenomena (astro-ph.HE)
Supermassive black hole
Astronomy and Astrophysics
Astrophysics - Astrophysics of Galaxies
Galaxy
Accretion (astrophysics)
13. Climate action
Astrophysics of Galaxies (astro-ph.GA)
Astrophysics::Earth and Planetary Astrophysics
Astrophysics - High Energy Astrophysical Phenomena
Flare
Zdroj: Nature Astronomy, 3, pp. 242-250
Nature Astronomy, 3, 242-250
ISSN: 2397-3366
Popis: Accreting supermassive black holes (SMBHs) can exhibit variable emission across the electromagnetic spectrum and over a broad range of timescales. The variability of active galactic nuclei (AGNs) in the ultraviolet and optical is usually at the few tens of per cent level over timescales of hours to weeks. Recently, rare, more dramatic changes to the emission from accreting SMBHs have been observed, including tidal disruption events, 'changing look' AGNs and other extreme variability objects. The physics behind the 're-ignition', enhancement and 'shut-down' of accretion onto SMBHs is not entirely understood. Here we present a rapid increase in ultraviolet-optical emission in the centre of a nearby galaxy, marking the onset of sudden increased accretion onto a SMBH. The optical spectrum of this flare, dubbed AT 2017bgt, exhibits a mix of emission features. Some are typical of luminous, unobscured AGNs, but others are likely driven by Bowen fluorescence - robustly linked here with high-velocity gas in the vicinity of the accreting SMBH. The spectral features and increased ultraviolet flux show little evolution over a period of at least 14 months. This disfavours the tidal disruption of a star as their origin, and instead suggests a longer-term event of intensified accretion. Together with two other recently reported events with similar properties, we define a new class of SMBH-related flares. This has important implications for the classification of different types of enhanced accretion onto SMBHs.
Comment: Published in Nature Astronomy
Databáze: OpenAIRE
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