Constraining the lensing of binary black holes from their stochastic background

Understand

Gravitational waves (GWs) are subject to gravitational lensing in the same way as electromagnetic radiation.

• However, to date, no unequivocal observation of a lensed GW transient has been reported.
• Independently, GW observatories continue to search for the stochastic GW signal which is produced by many transient events at high redshift.
• We exploit a surprising connection between the lensing of individual transients and limits to the background radiation produced by the unresolved population of binary back hole mergers: we show that it constrains the fraction of individually resolvable lensed binary black holes to less than $\sim 4\times 10^{-5}$ at present sensitivity.