Dynamic Lasing of Axion Clusters

TL;DR

The paper investigates stimulated decay of dense axion clusters under self-gravity, formulating a Boltzmann-based, dynamic lasing model that couples axion and photon populations with gravitational compression. It derives a set of coupled evolution equations and demonstrates, through numerical examples, that gravitational collapse can ignite or amplify lasing even when stationary thresholds would fail, producing transient photon bursts and leaving tiny remnants. The work suggests dynamic axion lasing as a plausible source for FRB-like signals, including repeaters, and highlights potential cosmological implications of lasing on early density perturbations. Overall, it extends previous stationary analyses by showing how gravity-driven compression can drive rapid, observable photon production from axion DM in a strongly non-equilibrium, quantum coherent context.

Abstract

We examine high-density axion clusters under gravitational compression. These are transient events in which the majority of axions are rapidly converted into photons, with some configurations producing photon signals with distinctive and characteristic patterns. We estimated the mass of the remnant objects and note that some could be black holes while in some cases it may be possible to identify the emitted photons with a robust class of fast radio bursts.

Figures (7)

• Figure 1: Number densities of axions, photons, and fast axions versus time during the stimulated emission from a cluster consisting of $m_a=10^{-4}$ eV axions with total mass $M_0=0.1 M_\odot$ and radius $R_0=1.8\times10^{-4} R_\odot$, based on the original stationary model.
• Figure 2: Number densities of axions, photons, and fast axions versus time during the stimulated emission from a cold cluster consisting of $m_a=10^{-4}$ eV axions with total mass $M_0=0.1 M_\odot$ and radius $R_0=1.8\times10^{-4} R_\odot$, based on the dynamical model.
• Figure 3: Number densities of axions and photons versus time after the stimulated emission from the cold cluster consisting of $m_a=10^{-4}$ eV axions with total mass $M_0=0.1 M_\odot$ and radius $R_0=1.8\times10^{-4} R_\odot$, based on the dynamical model(top). Reduction of the radius of the cluster from the combined effects of gravitational compression and stimulated emission of axions(Bottom left). Reduction of the radius of the cluster from the effect of gravitational compression only(Bottom right).
• Figure 4: Number densities(top) and total numbers(bottom) of axions and photons versus time during the stimulated emission from a warm cluster consisting of $m_a=10^{-4}$ eV axions with total mass $M_0=0.1 M_\odot$ and radius $R_0=1.8\times10^{-4} R_\odot$, based on the dynamical model.
• Figure 5: Velocity(left) and radius(right) of the warm cluster consisting of $m_a=10^{-4}$ eV axions with total mass $M_0=0.1 M_\odot$ and initial radius $R_0=1.8\times10^{-4} R_\odot$, affected by both gravitational compression and stimulated emission of axions, based on the dynamical model.