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
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