Cosmological angular momentum from quantum rotation

TL;DR

This paper introduces a new mechanism where quantum fluctuations during inflation generate cosmic angular momentum, potentially explaining black hole spins and linking early universe physics to observable gravitational waves.

Contribution

It proposes a novel quantum inflationary process that directly produces cosmic angular momentum, differing from traditional tidal torque theories.

Findings

Primordial black holes can acquire high spins (.1-1) from this mechanism.

Enhanced small-scale power spectra lead to detectable black hole abundances.

The model predicts a distinct spin distribution testable by gravitational-wave observations.

Abstract

The origin of cosmic angular momentum is a fundamental question in structure formation. We propose a novel mechanism that generates spatial angular momentum directly from quantum fluctuations during inflation. A spectator complex scalar field with global U(1) symmetry stores internal angular momentum via field-space rotation. Inflationary perturbations create spatial gradients that, upon horizon re-entry, couple to the background charge density and source a bulk momentum flow. During nonspherical gravitational collapse, this flow converts into net angular momentum. For primordial black holes forming from such collapse, the dimensionless spin can reach \(\chi\sim 0.1-1\) when the small-scale power spectrum is enhanced to produce detectable abundances-far exceeding tidal torque theory predictions. This establishes a testable link between inflation, primordial perturbations, and black hole spin distributions accessible to gravitational-wave observations.