Exploring the spectral shape of gravitational waves induced by primordial scalar perturbations and connection with the primordial black hole scenarios

Abstract

There is a growing expectation that the gravitational wave detectors will start probing the stochastic gravitational wave backgrounds in the following years. We explore the spectral shapes of gravitational waves induced to second order by scalar perturbations and presumably have been produced in the early universe. We calculate the gravitational wave spectra generated during radiation and kination eras together with the associated primordial black hole counterpart. We employ power spectra for the primordial curvature perturbation generated by α-attractors and non-minimal derivative coupling inflation models as well as Gaussian and delta-type shapes. We demonstrate the ability of the tensor modes to constrain the spectrum of the primordial curvature perturbations and discriminate among inflationary models. Gravitational wave production during kination and radiation era can also be distinguished by their spectral shapes and amplitudes.

Scalar Induced Gravitational Waves Review

“…More general thermal histories are studied in Refs. [64,[72][73][74][75][76]. The impact of additional free streaming particles is studied in Ref.…”

A topic review on probing primordial black hole dark matter with scalar induced gravitational waves

“…(2020a) ; Fu et al. (2020) ; Dalianis and Kritos (2021) ; Yi et al. (2020a) ; Dalianis (2020) ; Aldabergenov et al.…”

Primordial black holes and remnants of primordial black holes as dark matter: inflationary model building and observational constraints

“…The spectral shape for the Ω IGW (t 0 , f ), depends on the features of the source, the scalar spectrum P R (k). It maximizes at a frequency f p IGW , in a little offset from k p /2π, depending on the width of the P R (k) [50,51]. It is interesting to mention that, for the radiation domination case at least, the P R (k) shape is projected in a much more informative manner onto the IGW spectrum than on the PBH mass distribution, which is predominantly monochromatic.…”

“…[49] . For the early kination era with transition to radiation, eKD→RD, the density parameter of IGWs is given by [50]…”

“…For further analysis and comments we refer the reader to Ref. [50] where explicit scalar spectra and inflationary models are discussed and discriminated.…”