http://arxiv.org/abs/2211.13604
Massive objects located between Earth and a compact binary merger can act as a magnifying glass improving the sensitivity of gravitational wave detectors to distant events. A point mass lens between the detector and the source can manifest itself either through an amplification of the gravitational wave signal in a frequency dependent manner that is maximum at merger or through magnification combined with the appearance of a second image that interferes with the first creating a regular, predictable pattern. We map the increase in the signal to noise ratio for upcoming LVK observations as a function of the mass of the lens $M_L$ and dimensionless source position y for any point mass lens between the detector and the binary source. We find that most microlensing is silent with mismatch under $10\%$ and may never be identified as lensed. To quantify detectability, we compute the optimal match between the lensed waveform and the waveforms in the unlensed template bank and provide a map of the match. The higher the mismatch with unlensed templates, the more detectable lensing is. Furthermore, we estimate the probability of lensing, and find that the redshift to which binary mergers are visible with the LVK increases from $z \approx 1$ to $z\approx 3.2$ for a total detected mass $M_{det} = 120 M_\odot$. The overall probability of lensing is $<20\%$ of all detectable events above the threshold SNR for $M_{det} = 120 M_\odot$ and $<5\%$ for more common events with $M_{det} = 60 M_\odot$. We find that there is a selection bias for detectable lensing that favors events that are close to the line of sight $y \lesssim 0.5$. Black hole binary searches could thus improve their sensitivity by introducing a prior that takes the bias into account.
R. Bondarescu, H. Ubach, O. Bulashenko, et. al.
Mon, 28 Nov 22
43/93
Comments: 17 pages, 12 Figures, Submitted to Phys. Rev. D