Microlensing of long-duration gravitational wave signals originating from Galactic sources

Abstract

Detection of quasi-monochromatic, long-duration (continuous) gravitational wave radiation emitted by, e.g., asymmetric rotating neutron stars in our Galaxy requires a long observation time to distinguish it from the detector's noise. If this signal is additionally microlensed by a lensing object located in the Galaxy, its magnitude would be temporarily magnified, which may lead to its discovery and allow probing of the physical nature of the lensing object and the source. We study the observational effect of microlensing of continuous gravitational wave signals for Galactic sources and lenses in the point mass lens approximation. In particular, we examine the regions of the parameter space that are promising for lensed CW searches, and perform example simulations to demonstrate how the lensing effect affects the continuous-wave signal. We show that an analytical lensing pattern can be identified from the lensed continuous wave signal using the Time-Domain F-statistic search, as the estimated signal-to-noise ratio in each time-domain segment scales directly with the amplification factor.