Diffractive lensing of nano-Hertz gravitational waves emitted from supermassive binary black holes by intervening galaxies

Abstract Pulsar timing array (PTA) experiments are expected to detect nano-Hertz gravitational waves (GWs) emitted from individual inspiralling supermassive binary black holes (SMBBHs). The GW signals a small fraction of these SMBBHs may be diffractively lensed by intervening galaxies. In this paper, we investigate the diffractive lensing effects on continuous and estimate detectable number such PTAs, as Chinese PTA (CPTA) Square Kilometer Array (SKA) PTA. We find that amplitude only amplified factor ∼1.01 − 1.14 ($16~{{\%}}-84~{{\%}}$ range) phase shift somewhat due lensing, significantly different those strongly high frequency compact mergers in geometric optics. $\sim 0.01~{{\%}}$ all detected future foreground galaxies (i.e., up ∼106 for CPTA ∼289 SKA-PTA). However, difficult distinguished without observations only. further discuss possibility about identification via electromagnetic detection their host or active galactic nuclei.