The Tidal Disruption Event AT2021ehb : Evidence of Relativistic Disk Reflection, and Rapid Evolution of the Disk-Corona System
dc.contributor.author | Yao, Yuhan | |
dc.contributor.author | Lu, Wenbin | |
dc.contributor.author | Guolo, Muryel | |
dc.contributor.author | Pasham, Dheeraj R. | |
dc.contributor.author | Gezari, Suvi | |
dc.contributor.author | Gilfanov, Marat | |
dc.contributor.author | Gendreau, Keith C. | |
dc.contributor.author | Harrison, Fiona | |
dc.contributor.author | Cenko, S. Bradley | |
dc.contributor.author | Kulkarni, S. R. | |
dc.contributor.author | Miller, Jon M. | |
dc.contributor.author | Walton, Dominic J. | |
dc.contributor.author | García, Javier A. | |
dc.contributor.author | Velzen, Sjoert van | |
dc.contributor.author | Alexander, Kate D. | |
dc.contributor.author | Miller-Jones, James C. A. | |
dc.contributor.author | Nicholl, Matt | |
dc.contributor.author | Hammerstein, Erica | |
dc.contributor.author | Medvedev, Pavel | |
dc.contributor.author | Stern, Daniel | |
dc.contributor.author | Ravi, Vikram | |
dc.contributor.author | Sunyaev, R. | |
dc.contributor.author | Bloom, Joshua S. | |
dc.contributor.author | Graham, Matthew J. | |
dc.contributor.author | Kool, Erik C. | |
dc.contributor.author | Mahabal, Ashish A. | |
dc.contributor.author | Masci, Frank J. | |
dc.contributor.author | Purdum, Josiah | |
dc.contributor.author | Rusholme, Ben | |
dc.contributor.author | Sharma, Yashvi | |
dc.contributor.author | Smith, Roger | |
dc.contributor.author | Sollerman, Jesper | |
dc.date.accessioned | 2023-02-20T17:00:01Z | |
dc.date.available | 2023-02-20T17:00:01Z | |
dc.date.issued | 2022-09-15 | |
dc.identifier.citation | Yao , 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.issn | 0004-637X | |
dc.identifier.other | ArXiv: http://arxiv.org/abs/2206.12713v2 | |
dc.identifier.other | ORCID: /0000-0001-5819-3552/work/129622124 | |
dc.identifier.uri | http://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.abstract | We 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.extent | 25 | |
dc.format.extent | 6155666 | |
dc.language.iso | eng | |
dc.relation.ispartof | The Astrophysical Journal | |
dc.subject | astro-ph.HE | |
dc.title | The Tidal Disruption Event AT2021ehb : Evidence of Relativistic Disk Reflection, and Rapid Evolution of the Disk-Corona System | en |
dc.contributor.institution | School of Physics, Engineering & Computer Science | |
dc.contributor.institution | Centre for Astrophysics Research (CAR) | |
dc.contributor.institution | Department of Physics, Astronomy and Mathematics | |
dc.description.status | Peer reviewed | |
rioxxterms.versionofrecord | 10.3847/1538-4357/ac898a | |
rioxxterms.type | Journal Article/Review | |
herts.preservation.rarelyaccessed | true |