# 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.

## Key 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.