Light Curves of Partial Tidal Disruption Events

TL;DR

This paper investigates partial tidal disruption events (PTDEs), calculating their rates, light curves, and spectra, highlighting their potential for studying black hole accretion processes in a clean environment.

Contribution

It provides the first detailed calculations of PTDE event rates, light curves, and spectral features, emphasizing their observational signatures and differences from full TDEs.

Findings

PTDEs occur more frequently than full TDEs, especially around larger black holes.

Detection rate of PTDEs by ZTF is about dozens per year.

PTDE light curves exhibit double peaks with UV-peaking spectra.

Abstract

Tidal disruption events (TDEs) can uncover the quiescent black holes (BHs) at the center of galaxies and also offer a promising method to study them. In a partial TDE (PTDE), the BH's tidal force cannot fully disrupt the star, so the stellar core survives and only a varied portion of the stellar mass is bound to the BH and feeds it. We calculate the event rate of PTDEs and full TDEs (FTDEs). In general, the event rate of PTDEs is higher than that of FTDEs, especially for the larger BHs. And the detection rate of PTDEs is about dozens per year by Zwicky Transient Factory (ZTF). During the circularization process of the debris stream in PTDEs, no outflow can be launched due to the efficient radiative diffusion. The circularized debris ring then experiences viscous evolution and forms an accretion disk. We calculate the light curves of PTDEs contributed by these two processes, along with their radiation temperature evolution. The light curves have double peaks and the spectra peak in UV. Without obscuration or reprocessing of the radiation by an outflow, PTDEs provide a clean environment to study the circularization and transient disk formation in TDEs.