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dc.contributor.authorYao, Yuhan
dc.contributor.authorLu, Wenbin
dc.contributor.authorGuolo, Muryel
dc.contributor.authorPasham, Dheeraj R.
dc.contributor.authorGezari, Suvi
dc.contributor.authorGilfanov, Marat
dc.contributor.authorGendreau, Keith C.
dc.contributor.authorHarrison, Fiona
dc.contributor.authorCenko, S. Bradley
dc.contributor.authorKulkarni, S. R.
dc.contributor.authorMiller, Jon M.
dc.contributor.authorWalton, Dominic J.
dc.contributor.authorGarcía, Javier A.
dc.contributor.authorVelzen, Sjoert van
dc.contributor.authorAlexander, Kate D.
dc.contributor.authorMiller-Jones, James C. A.
dc.contributor.authorNicholl, Matt
dc.contributor.authorHammerstein, Erica
dc.contributor.authorMedvedev, Pavel
dc.contributor.authorStern, Daniel
dc.contributor.authorRavi, Vikram
dc.contributor.authorSunyaev, R.
dc.contributor.authorBloom, Joshua S.
dc.contributor.authorGraham, Matthew J.
dc.contributor.authorKool, Erik C.
dc.contributor.authorMahabal, Ashish A.
dc.contributor.authorMasci, Frank J.
dc.contributor.authorPurdum, Josiah
dc.contributor.authorRusholme, Ben
dc.contributor.authorSharma, Yashvi
dc.contributor.authorSmith, Roger
dc.contributor.authorSollerman, Jesper
dc.date.accessioned2023-02-20T17:00:01Z
dc.date.available2023-02-20T17:00:01Z
dc.date.issued2022-09-15
dc.identifier.citationYao , Y , Lu , W , Guolo , M , Pasham , D R , Gezari , S , Gilfanov , M , Gendreau , K C , Harrison , F , Cenko , S B , Kulkarni , S R , Miller , J M , Walton , D J , García , J A , Velzen , S V , Alexander , K D , Miller-Jones , J C A , Nicholl , M , Hammerstein , E , Medvedev , P , Stern , D , Ravi , V , Sunyaev , R , Bloom , J S , Graham , M J , Kool , E C , Mahabal , A A , Masci , F J , Purdum , J , Rusholme , B , Sharma , Y , Smith , R & Sollerman , J 2022 , ' The Tidal Disruption Event AT2021ehb : Evidence of Relativistic Disk Reflection, and Rapid Evolution of the Disk-Corona System ' , The Astrophysical Journal , vol. 937 , no. 1 . https://doi.org/10.3847/1538-4357/ac898a
dc.identifier.issn0004-637X
dc.identifier.otherArXiv: http://arxiv.org/abs/2206.12713v2
dc.identifier.otherORCID: /0000-0001-5819-3552/work/129622124
dc.identifier.urihttp://hdl.handle.net/2299/26069
dc.description© 2022. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/
dc.description.abstractWe present X-ray, UV, optical, and radio observations of the nearby ($\approx78$ Mpc) tidal disruption event (TDE) AT2021ehb/ZTF21aanxhjv during its first 430 days of evolution. AT2021ehb occurs in the nucleus of a galaxy hosting a $\approx 10^{7}\,M_\odot$ black hole ($M_{\rm BH}$ inferred from host galaxy scaling relations). High-cadence Swift and NICER monitoring reveals a delayed X-ray brightening. The spectrum first undergoes a gradual ${\rm soft }\rightarrow{\rm hard}$ transition and then suddenly turns soft again within 3 days at $\delta t\approx 272$ days during which the X-ray flux drops by a factor of ten. In the joint NICER+NuSTAR observation ($\delta t =264$ days, harder state), we observe a prominent non-thermal component up to 30 keV and an extremely broad emission line in the iron K band. The bolometric luminosity of AT2021ehb reaches a maximum of $6.0^{+10.4}_{-3.8}\% L_{\rm Edd}$ when the X-ray spectrum is the hardest. During the dramatic X-ray evolution, no radio emission is detected, the UV/optical luminosity stays relatively constant, and the optical spectra are featureless. We propose the following interpretations: (i) the ${\rm soft }\rightarrow{\rm hard}$ transition may be caused by the gradual formation of a magnetically dominated corona; (ii) hard X-ray photons escape from the system along solid angles with low scattering optical depth ($\sim\,$a few) whereas the UV/optical emission is likely generated by reprocessing materials with much larger column density -- the system is highly aspherical; (iii) the abrupt X-ray flux drop may be triggered by the thermal-viscous instability in the inner accretion flow leading to a much thinner disk.en
dc.format.extent25
dc.format.extent6155666
dc.language.isoeng
dc.relation.ispartofThe Astrophysical Journal
dc.subjectastro-ph.HE
dc.titleThe Tidal Disruption Event AT2021ehb : Evidence of Relativistic Disk Reflection, and Rapid Evolution of the Disk-Corona Systemen
dc.contributor.institutionSchool of Physics, Engineering & Computer Science
dc.contributor.institutionCentre for Astrophysics Research
dc.contributor.institutionDepartment of Physics, Astronomy and Mathematics
dc.description.statusPeer reviewed
rioxxterms.versionofrecord10.3847/1538-4357/ac898a
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue


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