超轻暗物质重组后磁生成中的数值反作用与有限时间能量转移
Numerical Backreaction and Finite-Time Energy Transfer in Post-Recombination Magnetogenesis from Ultralight Dark Matter
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中文总结 AI 辅助
研究超轻暗物质驱动的重组后磁生成中规范场产生，追踪$\phi$模式与规范场模式耦合演化，数值工作证实分析结果，确定反作用关闭共振的情况及不同参数下能量转移到光子时的${\cal{F}}$情况。
中文摘要 AI 辅助
我们研究了由与电磁耦合的超轻赝标量暗物质场$\phi$驱动的重组后磁生成场景中的规范场产生。先前的分析工作表明，均匀振荡的$\phi$背景可通过快子和窄带共振通道激发规范场模式。在此，我们追踪在膨胀背景中均匀$\phi$模式和两种螺旋性规范场模式的耦合演化。我们的数值工作证实了先前近似分析处理中得到的规范粒子谱结果。此外，我们的研究使我们能够确定反作用何时关闭共振。我们发现，对于快子不稳定性带打开的参数值，反作用直到初始暗物质能量密度的量级为一的分数${\cal{F}}$转移到光子时才关闭共振，且这发生在比哈勃时间短的时间尺度上。在仅窄共振带打开的参数范围内，${\cal{F}}$最终达到量级为一，但发生的时间随有效耦合常数减小而增加，因此${\cal{F}}$直到现在可能仍可忽略不计。
英文摘要
We study gauge-field production in a post-recombination magnetogenesis scenario driven by an ultralight pseudoscalar dark matter field $ϕ$ coupled to electromagnetism. Previous analytical work has shown that a homogeneous oscillating $ϕ$ background can excite gauge field modes through tachyonic and narrow-band resonance channels. Here we follow the coupled evolution of the homogeneous $ϕ$ mode and gauge field modes of both helicities in an expanding background. Our numerical work confirms the results for the spectra of produced gauge particles obtained in the previous approximate analytical treatments. In addition, our study allows us to determine when back-reaction shuts off the resonance. We find that for parameter values for which the tachyonic instability band is open, back-reaction does not shut off the resonance until a fraction ${\cal{F}}$ of order one of the initial dark matter energy density has been transferred to photons, and this happens on a time scale which is short compared to the Hubble time. In the parameter range in which only the narrow resonance band is open, ${\cal{F}}$ eventually reaches order one, but the time when this happens increases as the effective coupling constant decreases, and therefore ${\cal{F}}$ may remain negligible until the present time.
