Primordial black holes and induced gravitational waves from localized features in DBI inflation

Abstract

We investigate primordial black hole formation in a Dirac-Born-Infeld inflationary framework in which the background dynamics are determined by explicit functional forms of the inflaton potential $V(\varphi )$ and the warp factor $f(\varphi )$. The background equations are solved numerically to obtain the evolution of the slow-roll parameters. We show that a localized feature in the potential, accompanied by a correlated structure in the warp factor, dynamically induces a transient suppression of the slow-roll parameter, leading to a short-lived non-attractor phase. This behavior generates an enhancement of the curvature power spectrum on small scales, while preserving consistency with CMB-scale observables. The Mukhanov-Sasaki equation is then solved numerically to compute the resulting power spectrum, which exhibits narrow and localized peaks in the PBH abundance across different mass ranges. We also evaluate the associated stochastic background of induced gravitational waves and find that the predicted signal can fall within the sensitivity bands of future pulsar timing arrays and space-based interferometers, depending on the scale of the inflationary feature. A parameter scan in the $(r,n_s)$ plane shows that the large-scale predictions remain consistent with current observational constraints.

17 pages, 5 figures, 1 table

References in corpus (12)

• Primordial Black Holes as Dark Matter: Recent Developments
• Gravitational Wave Spectrum Induced by Primordial Scalar Perturbations
• Gravitational-wave sensitivity curves
• The cosmological gravitational wave background from primordial density perturbations
• Cosmic microwave background limits on accreting primordial black holes
• The merger rate of primordial-black-hole binaries
• Constraints on Earth-mass primordial black holes from OGLE 5-year microlensing events
• CMB bounds on disk-accreting massive Primordial Black Holes
• Primordial black hole formation in the radiative era: investigation of the critical nature of the collapse
• Calculating the mass spectrum of primordial black holes
• Curvature profiles as initial conditions for primordial black hole formation
• Planck and BICEP/Keck Array 2018 constraints on primordial gravitational waves and perspectives for future B-mode polarization measurements