Lensing of gravitational waves from tidal disruption events

TL;DR

This paper studies how gravitational lensing affects the detection of gravitational waves from tidal disruption events, predicting detection rates for future space-based observatories like LISA and DECIGO.

Contribution

It models the lens distribution using a hybrid approach and estimates the number of lensed TDEs detectable by upcoming GW observatories.

Findings

LISA is unlikely to detect TDEs even with lensing effects.

DECIGO could detect approximately 16 strongly lensed globular TDEs.

DECIGO could detect around 135 strongly lensed nuclear TDEs.

Abstract

In this work, we investigate the effect of gravitational lensing on the gravitational wave (GW) signals of a population of tidal disruption events (TDEs). We estimate the number of lensed-magnified signals that we expect to detect with future space-based GW observatories, in particular LISA and DECIGO. We model the lens distribution using an hybrid approach that combines semi-analytic methods with numerical results from ray tracing simulations. We divide the TDE population in two classes, nuclear TDEs (main sequence stars tidally disrupted by massive black holes in the cores of galaxies) and globular TDEs (white dwarfs tidally disrupted by intermediate mass black holes in globular clusters). We find that, even considering the effect of lensing, LISA will not be able to observe any TDEs, while DECIGO could detect $\sim$16 strongly lensed ($\mu>2$) globular TDEs and $\sim$135 strongly lensed nuclear TDEs, over an observational period of 10 years. Our results reveal the role that lensing will play in future deci-Hertz GW observatories, indicating exciting multi-messenger opportunities with TDEs but at same time signalling the need to develop adequate data analysis techniques to correctly reconstruct the astrophysical properties of the source.