Primordial black holes with anisotropic hair

TL;DR

This paper proposes a mechanism where anisotropic vector fields during inflation can lead to anisotropic enhancements in curvature perturbations, potentially affecting primordial black hole formation and testing the cosmic no-hair conjecture.

Contribution

It introduces a new model linking vector fields to anisotropic primordial black hole formation during inflation.

Findings

Anisotropic constant modes dominate the power spectrum under strong mixing.

Statistical anisotropy in PBH formation may be unavoidable in anisotropic inflation.

Provides a novel way to probe vector fields during inflation.

Abstract

A mechanism for generating anisotropic enhancements of the curvature perturbation through a vector field is proposed. We find that when the mixing between the inflaton perturbation and the vector-field perturbation is sufficiently strong in the anisotropic inflation, the power spectrum becomes dominated by anisotropic constant modes. This suggests that statistical anisotropy in primordial black hole (PBH) formation may be inevitable if inflation undergoes an anisotropic inflationary phase. Our findings offer a novel approach to probe vector fields during inflation and to test the cosmic no-hair conjecture.