Relativistic collapse of axion stars

TL;DR

This paper investigates the gravitational collapse of axion fields under spherical symmetry, using a simplified numerical scheme to efficiently identify conditions leading to black holes, axion stars, or Bosenova explosions.

Contribution

It introduces a faster, simpler numerical method for simulating axion field collapse and maps out the parameter space for different collapse outcomes.

Findings

Identifies parameter regions for black hole formation

Maps conditions for axion star stability

Determines parameters leading to Bosenova explosions

Abstract

We study the gravitational collapse of an axion field in null coordinates, assuming spherical symmetry. Compared with previous studies, we use a simpler numerical scheme which can run, for relevant parameters, in a few minutes or less on a desktop computer. We use it to accurately determine the domains of parameter space in which the axion field forms a black hole, an axion star or a relativistic Bosenova.