paper

Primordial black holes and secondary gravitational waves from k/G inflation

arXiv:2001.05909 · doi:10.1103/PhysRevD.101.103515

Abstract

The possibility that in the mass range around most of dark matter constitutes of primordial black holes (PBHs) is a very interesting topic. To produce PBHs with this mass, the primordial scalar power spectrum needs to be enhanced to the order of 0.01 at the scale . The enhanced power spectrum also produces large secondary gravitational waves at the mHz band. A phenomenological delta function power spectrum is usually used to discuss the production of PBHs and secondary gravitational waves. Based on G and k inflations, we propose a new mechanism to enhance the power spectrum at small scales by introducing a non-canonical kinetic term with the function having a peak. Away from the peak, is negligible and we recover the usual slow-roll inflation which is constrained by the cosmic microwave background anisotrpy observations. Around the peak, the slow-roll inflation transiently turns to ultra slow-roll inflation. The enhancement of the power spectrum can be obtained with generic potentials, and there is no need to fine tune the parameters in . The energy spectrum of secondary gravitational waves have the characteristic power law behaviour and is testable by pulsar timing array and space based gravitational wave detectors.

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