TY - JOUR
T1 - Compact binaries through a lens
T2 - Silent versus detectable microlensing for the LIGO-Virgo-KAGRA gravitational wave observatories
AU - Bondarescu, Ruxandra
AU - Ubach, Helena
AU - Bulashenko, Oleg
AU - Lundgren, Andrew
N1 - Funding Information:
The authors are grateful to the members of the Gravitational Waves research group from ICC UB for their continual advice and support. We particularly thank Mark Gieles, Tomas Andrade, Juan Trenado, and Daniel Marín Pina. We also thank ICC secretaries, Esther Pallarés Guimerà and Anna Argudo who go well-beyond their job to keep everything running smoothly. We are also grateful to Tom Collett and David Bacon from ICG Portsmouth for numerous helpful discussions. We acknowledge support from the Spanish Ministry of Science and Innovation through Grants No. PID2021-125485NB-C22 and No. CEX2019-000918-M funded by MCIN/AEI/10.13039/501100011033. R. B. and O. B. acknowledge support from the AGAUR through Grant No. SGR-2021-01069. A. L. is supported by STFC Grants No. ST/T000550/1 and No. ST/V005715/1. This work has used the p y cbc python package, . The authors are grateful for computational resources provided by the LIGO Laboratory and Cardiff University and supported by National Science Foundation Grants No. PHY-0757058 and No. PHY-0823459 and STFC Grant No. ST/I006285/1.
Publisher Copyright:
© 2023 American Physical Society. uk.
PY - 2023/10/17
Y1 - 2023/10/17
N2 - Massive objects located between Earth and a compact binary merger can act as gravitational lenses magnifying signals and improving the sensitivity of gravitational wave detectors to distant events. Depending on the parameters of the system, a point-mass lens between the detector and the source can either lead to a smooth frequency-dependent amplification of the gravitational wave signal, or 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 LIGO-Virgo-KAGRA (LVK) observations as a function of the mass of the lens ML and a dimensionless source position y for any point-mass lens between the detector and the binary source. 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≈1 to z≈3.2 for a total detected mass Mdet=120M⊙. The overall probability of lensing is <20% of all detectable events above the threshold SNR for Mdet=120M⊙ and <5% for more common events with Mdet=60M⊙. We find that there is a selection bias for detectable lensing that favors events that are close to the line of sight y≲0.5. Black hole binary searches could thus improve their sensitivity by taking this bias into account. Moreover, the match, the signal-to-noise ratio increase due to lensing, and the probability of lensing are only weakly dependent on the noise curve of the detector with very similar results for both the O3 and predicted O4 noise power spectral densities. These results are upper limits that assume all dark matter is composed of 300M⊙ point-mass lenses.
AB - Massive objects located between Earth and a compact binary merger can act as gravitational lenses magnifying signals and improving the sensitivity of gravitational wave detectors to distant events. Depending on the parameters of the system, a point-mass lens between the detector and the source can either lead to a smooth frequency-dependent amplification of the gravitational wave signal, or 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 LIGO-Virgo-KAGRA (LVK) observations as a function of the mass of the lens ML and a dimensionless source position y for any point-mass lens between the detector and the binary source. 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≈1 to z≈3.2 for a total detected mass Mdet=120M⊙. The overall probability of lensing is <20% of all detectable events above the threshold SNR for Mdet=120M⊙ and <5% for more common events with Mdet=60M⊙. We find that there is a selection bias for detectable lensing that favors events that are close to the line of sight y≲0.5. Black hole binary searches could thus improve their sensitivity by taking this bias into account. Moreover, the match, the signal-to-noise ratio increase due to lensing, and the probability of lensing are only weakly dependent on the noise curve of the detector with very similar results for both the O3 and predicted O4 noise power spectral densities. These results are upper limits that assume all dark matter is composed of 300M⊙ point-mass lenses.
KW - UKRI
KW - STFC
KW - ST/T000550/1
KW - ST/V005715/1
UR - http://www.scopus.com/inward/record.url?scp=85178254606&partnerID=8YFLogxK
U2 - 10.1103/PhysRevD.108.084033
DO - 10.1103/PhysRevD.108.084033
M3 - Article
AN - SCOPUS:85178254606
SN - 2470-0010
VL - 108
JO - Physical Review D
JF - Physical Review D
IS - 8
M1 - 084033
ER -