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Rapid Dimming Follo...
Rapid Dimming Followed by a State Transition: A Study of the Highly Variable Nuclear Transient AT 2019avd over 1000+ Days
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- Wang, Yanan (author)
- University of Southampton,Chinese Academy of Sciences
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- Pasham, Dheeraj R. (author)
- Massachusetts Institute of Technology (MIT)
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- Altamirano, D. (author)
- University of Southampton
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- Gúrpide, Andrés (author)
- University of Southampton
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- Castro Segura, N. (author)
- University of Southampton
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- Middleton, Matthew (author)
- University of Southampton
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- Ji, Long (author)
- Sun Yat-Sen University
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- Del Palacio, Santiago, 1990 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Guolo, Muryel (author)
- Johns Hopkins University
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- Gandhi, Poshak (author)
- University of Southampton
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- Zhang, Shuang Nan (author)
- Chinese Academy of Sciences
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- Remillard, R. (author)
- Massachusetts Institute of Technology (MIT)
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- Lin, Dacheng (author)
- Northeastern University
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- Masterson, Megan (author)
- Massachusetts Institute of Technology (MIT)
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- Baldi, R. D. (author)
- Istituto di Radioastronomia,University of Southampton
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- Tombesi, Francesco (author)
- University of Maryland,Universita degli Studi di Roma Tor Vergata,University of Rome Tor Vergata,NASA Goddard Space Flight Center
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- Miller, Jon M. (author)
- University of Michigan
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- Zhang, Wenda (author)
- Chinese Academy of Sciences
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- Sanna, Andrea (author)
- Universita degli Studi di Cagliari,University of Cagliari
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(creator_code:org_t)
- 2024
- 2024
- English.
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In: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 962:1
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Abstract
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- The tidal disruption of a star around a supermassive black hole (SMBH) offers a unique opportunity to study accretion onto an SMBH on a human timescale. We present results from our 1000+ days monitoring campaign of AT 2019avd, a nuclear transient with tidal-disruption-event-like properties, with NICER, Swift, and Chandra. Our primary finding is that approximately 225 days following the peak of the X-ray emission, there is a rapid drop in luminosity exceeding 2 orders of magnitude. This X-ray dropoff is accompanied by X-ray spectral hardening, followed by a plateau phase of 740 days. During this phase, the spectral index decreases from 6.2 ± 1.1 to 2.3 ± 0.4, while the disk temperature remains constant. Additionally, we detect pronounced X-ray variability, with an average fractional rms amplitude of 47%, manifesting over timescales of a few dozen minutes. We propose that this phenomenon may be attributed to intervening clumpy outflows. The overall properties of AT 2019avd suggest that the accretion disk evolves from a super-Eddington to a sub-Eddington luminosity state, possibly associated with a compact jet. This evolution follows a pattern in the hardness-intensity diagram similar to that observed in stellar-mass BHs, supporting the mass invariance of accretion-ejection processes around BHs
Subject headings
- NATURVETENSKAP -- Fysik -- Subatomär fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Subatomic Physics (hsv//eng)
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
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- art (subject category)
- ref (subject category)
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- By the author/editor
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Wang, Yanan
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Pasham, Dheeraj ...
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Altamirano, D.
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Gúrpide, Andrés
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Castro Segura, N ...
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Middleton, Matth ...
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show more...
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Ji, Long
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Del Palacio, San ...
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Guolo, Muryel
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Gandhi, Poshak
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Zhang, Shuang Na ...
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Remillard, R.
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Lin, Dacheng
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Masterson, Megan
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Baldi, R. D.
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Tombesi, Frances ...
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Miller, Jon M.
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Zhang, Wenda
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Sanna, Andrea
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show less...
- About the subject
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Physical Science ...
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and Subatomic Physic ...
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Physical Science ...
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and Astronomy Astrop ...
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Astrophysical Jo ...
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Chalmers University of Technology