NANOGrav hints on planet-mass primordial black holes

Recently, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) claimed the detection of a stochastic common-spectrum process of the pulsar timing array (PTA) time residuals from their 12.5 year data, which might be the first detection of the stochastic background of gravitational waves (GWs). We show that the amplitude and the power index of such waves imply that they could be the secondary GWs induced by the peaked curvature perturbation with a dust-like post inflationary era with -0.091 less than or similar to w less than or similar to 0.048. Such stochastic background of GWs naturally predicts substantial existence of planet-mass primordial black holes (PBHs), which can be the lensing objects for the ultrashort-timescale microlensing events observed by the Optical Gravitational Lensing Experiment (OGLE).

Automated summary

Recently, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) claimed the first detection of the stochastic background of gravitational waves (GWs) through their analysis of pulsar timing array (PTA) time residuals. They found that these waves could be secondary GWs induced by peaked curvature perturbation in a dust-like post inflationary era with a power index, w, ranging from -0.091 to 0.048. The presence of the stochastic background of GWs also predicts the existence of planet-mass primordial black holes (PBHs), which could explain the ultrashort-timescale microlensing events observed by the Optical Gravitational Lensing Experiment (OGLE).