Electromagnetic instability of compact axion stars
Electromagnetic instability of compact axion stars
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DOI：
10.1103/physrevd.108.l061302
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发表时间：
2023-02
影响因子：
5
通讯作者：
Liina M. Chung-Jukko;Eugene A. Lim;D. Marsh;Josu C. Aurrekoetxea;Eloy de Jong;Bo-Xuan Ge
中科院分区：
文献类型：
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作者：
Liina M. Chung-Jukko;Eugene A. Lim;D. Marsh;Josu C. Aurrekoetxea;Eloy de Jong;Bo-Xuan Ge
如果暗物质是由轴子组成的，那么轴子恒星就应该在宇宙中大量存在。我们在完全非线性（3+1）数值相对论中证明了由于电磁chen - simons项引起的致密轴子星的不稳定性。我们证明了在临界耦合常数$g_{a\gamma}^\mathrm{crit} \propto M_s^{-1.35}$以上，质量为$M_s$的致密轴子星是不稳定的。不稳定性是由轴子与电磁场之间的参数共振引起的。稳定致密轴子恒星的存在需要与光子的近似普朗克抑制耦合。如果耦合超过临界值，则所有稳定的轴子星都必然是非致密的。不稳定的轴子恒星衰变后，会留下质量更小、密度更小的残骸。发射的辐射峰值频率为$\omega \sim 1/R_s$，其中$R_s$为轴子星半径。
If the dark matter is composed of axions, then axion stars are expected to be abundant in the Universe. We demonstrate in fully non-linear (3+1) numerical relativity the instability of compact axion stars due to the electromagnetic Chern-Simons term. We show that above the critical coupling constant $g_{a\gamma}^\mathrm{crit} \propto M_s^{-1.35}$, compact axion stars of mass $M_s$ are unstable. The instability is caused by parametric resonance between the axion and the electromagnetic field. The existence of stable compact axion stars requires approximately Planck-suppressed couplings to photons. If the coupling exceeds the critical value, then all stable axion stars are necessarily non-compact. Unstable axion stars decay leaving behind a less massive, less compact, remnant. The emitted radiation peaks at frequency $\omega \sim 1/R_s$, where $R_s$ is the axion star radius.