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Dynamical Unification of Tidal Disruption Events

Thomsen, Lars L. and Kwan, Tom M. and Dai, Lixin and Wu, Samantha C. and Roth, Nathaniel and Ramirez-Ruiz, Enrico (2022) Dynamical Unification of Tidal Disruption Events. Astrophysical Journal Letters, 937 (2). Art. No. L28. ISSN 2041-8205. doi:10.3847/2041-8213/ac911f.

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The ∼100 tidal disruption events (TDEs) observed so far exhibit a wide range of emission properties both at peak and over their lifetimes. Some TDEs radiate predominantly at X-ray energies, while others radiate chiefly at UV and optical wavelengths. While the peak luminosities across TDEs show distinct properties, the evolutionary behavior can also vary between TDEs with similar peak emission properties. In particular, for optical TDEs, while their UV and optical emissions decline somewhat following the fallback pattern, some events can greatly rebrighten in X-rays at late time. In this Letter, we conduct three-dimensional general relativistic radiation magnetohydrodynamics simulations of TDE accretion disks at varying accretion rates in the regime of super-Eddington accretion. We make use of Monte Carlo radiative transfer simulations to calculate the reprocessed spectra at various inclinations and at different evolutionary stages. We confirm the unified model proposed by Dai et al., which predicts that the observed emission largely depends on the viewing angle of the observer with respect to the disk orientation. Furthermore, we find that disks with higher accretion rates have elevated wind and disk densities, which increases the reprocessing of the high-energy radiation and thus generally augments the optical-to-X-ray flux ratio along a particular viewing angle. This implies that at later times, as the accretion level declines, we expect that more X-rays will leak out along intermediate viewing angles. Such dynamical model for TDEs can provide a natural explanation for the diversity in the emission properties observed in TDEs at peak and along their temporal evolution.

Item Type:Article
Related URLs:
URLURL TypeDescription
Thomsen, Lars L.0000-0003-4256-7059
Kwan, Tom M.0000-0003-0509-2541
Dai, Lixin0000-0002-9589-5235
Wu, Samantha C.0000-0003-2872-5153
Roth, Nathaniel0000-0002-6485-2259
Ramirez-Ruiz, Enrico0000-0003-2558-3102
Additional Information:We thank K. Auchettl, C. Bonnerot, M. Bulla, J. Garcia, S. Gezari, E. Kara, D. Kasen, C. Knigge, G. Leloudas, B. Mockler, N. Stone, and S. van Velzen for useful discussions. We also acknowledge the anonymous referee for constructive comments. L.T., T.K., and L.D. acknowledge the support from the Hong Kong Research Grants Council (HKU27305119, HKU17304821) and the National Natural Science Foundation of China (HKU12122309). E.R.-R. is grateful for support from the Heising-Simons Foundation, NSF (AST-1615881, AST-1911206, and AST-1852393), Swift (80NSSC21K1409, 80NSSC19K1391), and Chandra (GO9-20122X). This material is based on work supported by the National Science Foundation Graduate Research Fellowship under grant No. DGE-1745301. The simulations carried out for this project were performed on the HPC computing facilities offered by ITS at HKU and the Tianhe-2 supercluster.
Funding AgencyGrant Number
Research Grants Council of Hong KongHKU27305119
National Natural Science Foundation of ChinaHKU12122309
Heising-Simons FoundationUNSPECIFIED
NSF Graduate Research FellowshipDGE-1745301
Issue or Number:2
Record Number:CaltechAUTHORS:20221010-454096500.16
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117301
Deposited By: Research Services Depository
Deposited On:14 Oct 2022 17:55
Last Modified:14 Oct 2022 17:55

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