论文标题
如何抑制指数增长 - 轴心背景下光子的参数共振
How to suppress exponential growth -- on the parametric resonance of photons in an axion background
论文作者
论文摘要
轴轴 - 光子相互作用可以通过参数共振在冷轴背景的情况下通过参数共振导致电磁场的增强，对于频率接近一半轴质量的模式。在本文中，我们研究了轴突动量分散体的作用以及背景引力电位的作用，这可能会因重力红移而造成共振。我们通过分析和数值计算显示，仅当（a）（a）轴突动量扩散小于反向共振长度时，共振导致光子场的指数生长，并且（b）重力失谐距离长于谐振长度。对于现实的参数值，这两种效应都会强烈抑制共振并防止光子场的指数生长。特别是，由于我们的星系的重力引起的红移，还阻止了可观察到的频率范围内光子的共振，甚至假设所有暗物质都由完全冷的轴突冷凝物组成。对于低于$ \ sim 10^{ - 13} \，m_ \ odot $的轴向团块，动量扩展条件更具限制性，而对于更大的团块，红移条件占主导地位。
Axion--photon interactions can lead to an enhancement of the electromagnetic field by parametric resonance in the presence of a cold axion background, for modes with a frequency close to half the axion mass. In this paper, we study the role of the axion momentum dispersion as well as the effects of a background gravitational potential, which can detune the resonance due to gravitational redshift. We show, by analytical as well as numerical calculations, that the resonance leads to an exponential growth of the photon field only if (a) the axion momentum spread is smaller than the inverse resonance length, and (b) the gravitational detuning distance is longer than the resonance length. For realistic parameter values, both effects strongly suppress the resonance and prevent the exponential growth of the photon field. In particular, the redshift due to the gravitational potential of our galaxy prevents the resonance from developing for photons in the observable frequency range, even assuming that all the dark matter consists of a perfectly cold axion condensate. For axion clumps with masses below $\sim 10^{-13}\, M_\odot$, the momentum spread condition is more restrictive, whereas, for more massive clumps, the redshift condition dominates.
