Physics

Perturbation (astronomy)

LIGO

Mathematics

Hubble volume

Hubble's law

Scalar field

Parametric oscillator

Dark energy

Amplitude

Primordial black hole

Gravitational wave

Curvature

Inflation (cosmology)

Geometry

Cosmology

Quantum electrodynamics

Astrophysics

Quantum mechanics

Binary black hole

Classical mechanics

Physical review. D/Physical review. D.

We present a new realization of the resonant production of primordial black holes as well as gravitational waves in a two-stage inflation model consisting of a scalar field ϕwith an axion-monodromy-like periodic structure in the potential that governs the first stage and another field χwith a hilltop-like potential that dominates the second stage. The parametric resonance seeded by the periodic structure at the first stage amplifies the perturbations of both fields inside the Hubble radius. While the evolution of the background trajectory experiences a turn as the oscillatory barrier height increases, the amplified perturbations of χremain as they are and contribute to the final curvature perturbation. It turns out that the primordial power spectrum displays a significant resonant peak on small scales, which can lead to an abundant production of primordial black holes. Furthermore, gravitational waves are also generated from the resonantly enhanced field perturbations during inflation, the amplitude of which may be constrained by future gravitational wave interferometers.

Primordial black holes and gravitational waves from resonant amplification during inflation