Effect of lensing magnification on the apparent distribution of black hole mergers

Understand

The recent detection of gravitational waves indicates that stellar-mass black hole binaries are likely to be a key population of sources for forthcoming observations.

• With future upgrades, ground-based detectors could detect merging black hole binaries out to cosmological distances.
• Gravitational wave bursts from high redshifts ($z \gtrsim 1$) can be strongly magnified by gravitational lensing due to intervening galaxies along the line of sight.
• In the absence of electromagnetic counterparts, the mergers' intrinsic mass scale and redshift are degenerate with the unknown magnification factor $\mu$.