Astronomy and Astrophysics Seminars

# Accretion dynamics in tidal disruption events

## by Dr. Mageshwaran T. (DAA, TIFR)

Thursday, July 16, 2020 from to (Asia/Kolkata)
at Zoom Talk
 Description A tidal disruption event (TDE) occurs when a star is stripped into pieces due to the black hole's tidal gravity that exceeds the star's self-gravity. TDEs provides an excellent opportunity to study accretion dynamics. I will present the time-dependent accretion models for TDEs. We construct a relativistic thin disk accretion model that includes the mass addition due to infalling stellar debris with a mass fallback rate of $\dot{M}_f$ for both full and partial disruption TDEs. The mass fallback affects the disk evolution and the luminosity declines faster than the expected $L \propto \dot{M}_f$. Our relativistic accretion model is effective in the sub-Eddington regime. We also construct a non-relativistic accretion model for a super-Eddington disk with advection and without a fallback. The luminosity is super-Eddington initially and decreases to sub-Eddington on a time-scale of months to a year. Our model is useful in extracting the physical parameters such as black hole mass and spin, stellar mass, and the circularization time from observations. We will also show that TDEs can be used to build the black hole mass function using the inferred TDE rates from various surveys. We will also present the study on the correlation between the photon index and X-ray luminosity, and the spectral behaviour from TDE observations.