Astronomy and Astrophysics Seminars

Advection-dominated accretion disk corona modeling in tidal disruption events

by Dr. Mageshwaran T. (Chungbuk National University, South Korea)

Tuesday, January 31, 2023 from to (Asia/Kolkata)
at Hybrid ( AG-66 ) Meeting ID: 996 5230 9329 Passcode: 735855
Tidal disruption events (TDEs) provide a good probe for quiescent supermassive black holes (SMBHs) in the centers of inactive galaxies. A star is tidally disrupted by an SMBH when the star approaches the black hole closely enough that the black hole's tidal force exceeds the stellar self-gravity. The subsequent accretion of stellar debris falling onto the SMBH produces a characteristic flare lasting several months. The UV-to-X-ray spectral index and the Eddington ratio are correlated in TDEs, with non-thermal X-ray emission at low Eddington ratios. The corona surrounding the accretion disk is a non-thermal X-ray source. The corona above the accretion disk is heated via magnetic reconnections, and a fraction of the energy generated via viscous heating is transported to the corona by the magnetic fields. We construct a time-dependent and advection-dominated accretion disk- corona model for TDEs. We assume the disrupted debris will form a seed disk that evolves due to mass loss by accretion onto the black hole and mass gain by fallback of the debris. The X-ray blackbody temperature of the disk agrees with the observations, and the disk evolves from Eddington to sub-Eddington accretion. The presence of a corona impacts the spectral luminosity significantly for the sub-Eddington accretion and decreases the disk radiative efficiency. Our model is applicable to fit the observations with near-to-sub- Eddington accretion. 
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