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« Strong lensing of gravitational waves by galaxy clusters »

Graham P. Smith
School Physics Space Research, Univ. Birmingham (Birmingham, Royaume-Uni)

Strong gravitational lensing by massive galaxy clusters has played a key role in unveiling new galaxy populations at high redshift, and recently generated huge excitement and renewed interest in lensed transients. The predominance of >20Msolar black holes (BHs) in the early gravitational wave (GW) detections prompts speculation that one or more of the binary BH (BBH) sources might have been strongly-lensed and thus at higher redshift and have lower mass than inferred from the LIGO data alone. The detection of a strongly-lensed, i.e. multiply-imaged, gravitational wave (GW) source would be very exciting for many reasons, including constraints on the Hubble parameter from very precise time delay information, additional GW polarisation information available from the arrival of signal from a single GW source on multiple occasions at the LIGO/Virgo interferometers, and the best chance of detecting any electromagnetic radiation from a binary black hole (BBH) source thanks to the lens magnification. We show that the probability that one of the BBH GW detections to date is strongly-lensed is small but non-zero. We therefore present results from our optical observations of known strong-lensing clusters located within sky localisations of BBH sources detected by LIGO/Virgo during their second observing run, and comment on the future prospects for lensed GW detection.
mardi 15 mai 2018 - 11:15
Salle 281, Institut d'Astrophysique
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