When primordial black holes from sound speed resonance meet a stochastic background of gravitational waves

Abstract

As potential candidates of dark matter, primordial black holes (PBHs) are within the core scopes of various astronomical observations. In light of the explosive development of gravitational wave (GW) and radio astronomy, we thoroughly analyze a stochastic background of cosmological GWs, induced by overly large primordial density perturbations, with several spikes that was inspired by the sound speed resonance effect and can predict a particular pattern on the mass spectrum of PBHs. With a specific mechanism for PBHs formation, we for the first time perform the study of such induced GWs that originate from both the inflationary era and the radiation-dominated phase. We report that, besides the traditional process of generating GWs during the radiation-dominated phase, the contribution of the induced GWs in the sub-Hubble regime during inflation can become significant at the critical frequency band because of a narrow resonance effect. All contributions sum together to yield a specific profile of the energy spectrum of GWs that can be of observable interest in forthcoming astronomical experiments. Our study shed light on the possible joint probe of PBHs via various observational windows of multimessenger astronomy, including the search for electromagnetic effects with astronomical telescopes and the stochastic background of relic GWs with GW instruments.

Resonance instability of primordial gravitational waves during inflation in Chern–Simons gravity

“…The amplitude difference after horizon crossing between two resonant polarization modes originates mainly from the phase difference of h R and h L before the horizon crossing (see Fig. 4), which results from the difference of their equations of motion (14) when the Chern-Simons coupling is considered. Similar results can also be found in the other two cases.…”

“…The parameter resonance amplification of scalar perturbations during inflation has been widely discussed [13][14][15][16][17]. In this paper, we investigate the similar amplification of tensor perturbations with parity-violation caused by the gravitational Chern-Simons term coupled to an axion field that drives inflation while they are deep inside the horizon during inflation.…”

Primordial black holes formation in the inflationary model with field-dependent kinetic term for quartic and natural potentials

“…Furthermore, the PBHs formation is followed by the generation of the induced gravitational waves (GWs), when the primordial curvature perturbations enhance significantly [59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74]. In other words, after the horizon re-entry, the collapse of the overdense regions can generate large metric perturbations besides PBHs.…”

Listening to the sound of dark sector interactions with gravitational wave standard sirens

“…constraints on various aspects of fundamental physics, see e.g. [124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146] (see also the reviews [147,148]).…”