Challenges in the modelling of tidal disruption events lightcurves

TL;DR

This paper reviews recent advances in modeling tidal disruption event lightcurves, highlighting the impact of stellar structure, improved disc emission models, and potential relativistic effects near black holes.

Contribution

It introduces updated models for TDE lightcurves considering stellar structure, disc emission, and relativistic effects, expanding beyond the traditional $t^{-5/3}$ decay law.

Findings

Lightcurve rise depends on star’s internal structure

Optical/UV decline flatter than $t^{-5/3}$

Possible relativistic Lense-Thirring precession evidence

Abstract

In this contribution, I review the recent developments on the modelling of the lightcurve of tidal disruption events. Our understanding has evolved significantly from the earlier seminal results that imply a simple power-law decay of the bolometric light curve as $t^{-5/3}$. We now know that the details of the rise to the peak of the lightcurve is determined mainly by the internal structure of the disrupted star. We also have improved models for the disc thermal emission, showing that in this case the decline of the luminosity with time should be much flatter than the standard $t^{-5/3}$ law, especially in optical and UV wavelengths, while the X-ray lightcurve is generally best suited to track the bolometric one. Finally, we are just starting to explore the interesting general relativistic effects that might arise for such events, for which the tidal radius lies very close to the black hole event horizon. In particular, I describe here some possible evidences for relativistic Lense-Thirring precession from the light curve of the event Swift J1644.