Formation of primordial black holes (PBHs) requires a large root-mean-square amplitude of density fluctuations, which generate second-order tensor perturbations that can be compared with observational constraints. We show that pulsar timing data essentially rules out PBHs with 102–4 M⊙ which were previously considered as a candidate of intermediate-mass black hoes and that PBHs with mass range 1020–25 g which provide an astrophysical candidate for dark matter may be probed by future space-based laser interferometers.
Pulsar timing can constrain primordial black holes in the LIGO mass window
