Detectability of Strongly Gravitationally Lensed Tidal Disruption Events

TL;DR

This paper estimates the detection rates of strongly gravitationally lensed tidal disruption events (TDEs) in future all-sky surveys, highlighting the importance of survey depth and the potential for early detection to study TDE physics.

Contribution

It provides a statistical analysis of the detection rates of lensed TDEs based on survey limiting magnitudes, informing future survey strategies and early warning systems.

Findings

Detection rate increases with survey depth, reaching several tens to hundreds per year at 25-26 mag.

Limiting magnitudes of 21.2-21.5 mag are needed for at least 1 TDE per year detection.

Early identification of lensed TDE images can enable detailed monitoring of TDE evolution.

Abstract

More than 100 tidal disruption events (TDEs) have been detected at multi-bands, which can be viewed as extreme laboratories to investigate the accretion physics and gravity in the immediate vicinity of massive black holes. Future transient surveys are expected to detect several tens of thousands of TDEs, among which a small fraction may be strongly gravitationally lensed by intervening galaxies. In this paper, we statistically etsimate the detection rate of lensed TDEs, with dependence on the limiting magnitude of the transient all-sky surveys searching for them. We find that the requisite limiting magnitude for an all-sky transient survey to observe at least $1$ yr$^{-1}$ is $\gtrsim 21.3$, $21.2$, and $21.5$ mag in the $u$, $g$, and $z$ bands, respectively. If the limiting magnitude of the all-sky survey can reach $\sim 25-26$ mag in the $u$, $g$, and $z$ bands, the detection rate can be upto about several tens to hundreds per year. The discovery and identification of the first image of the lensed TDE can be taken as an early warning of the second and other subsequent images, which may enable detailed monitoring of the pre-peak photometry and spectroscopy evolution of the TDE. The additional early-stage information may help to constrain the dynamical and radiation processes involving in the TDEs.