Axion Star Bosenova in Axion Miniclusters

TL;DR

This paper investigates the conditions under which axion stars within miniclusters undergo bosenova explosions, emphasizing the role of self-interaction effects across different axion models.

Contribution

It incorporates axion self-interaction effects into the analysis of axion star stability and identifies parameter spaces where bosenova events are likely to occur.

Findings

Self-interaction can dominate axion star mass growth.

Bosenova occurs in a large fraction of parameter space for high overdensity miniclusters.

QCD axion bosenova can happen within the Universe's age for overdensities above 100.

Abstract

Axionic dark matter can form structures known as miniclusters that host an axion star at their center. The axion star feeds on the host, and the axion star mass may grow beyond its stability limit, leading to a potential bosenova. Since a dilute axion star has a stable mass limit only when self-interaction is considered, we include axion self-interaction effects in this paper, and specify the condition for bosenova in the QCD axion and temperature-independent axion-like particle parameter spaces. We find that self-interaction may dominate the mass growth of the axion star. For a minicluster with a large initial overdensity, bosenova occurs in a large fraction of axion parameter space. For the QCD axion, bosenova occurs within the age of the Universe for miniclusters with an initial overdensity $\delta\gtrsim 100$.