Speaker
Dr
Kyohei Mukaida
(Kavli IPMU)
Description
Primordial black holes (PBHs) are one of the candidates to explain the gravitational wave (GW) signals observed by the LIGO detectors. Among several phenomena in the early Universe, cosmic inflation is a major example to generate PBHs. In this case, the primordial curvature perturbation should be large enough to generate a sizable amount of PBHs, and thus we have several other probes to test this scenario. We point out that the current pulsar timing array (PTA) experiments already put severe constraints on GWs generated via the second-order effects, and that the observation of the cosmic microwave background (CMB) offers tight bounds on its small-scale distortions, such as mu-distortion. In particular, for simple inflation models, it is found that the scalar power spectrum should have a sharp peak at k ~ 10^6 Mpc^-1 to fulfill the required abundance of PBHs while evading constraints from the PTA experiments and the mu-distortion.
Primary author
Dr
Kyohei Mukaida
(Kavli IPMU)
