论文标题
早期宇宙中克尔黑洞的热力引力和引力波
Hot Gravitons and Gravitational Waves From Kerr Black Holes in the Early Universe
论文作者
论文摘要
早期宇宙中存在的任何大量黑洞都会随着物质而发展，随着空间的扩展而占总能量密度的越来越大。这促使我们考虑了早期宇宙的场景，其中包括一个由低质量（$ m <5 \ times 10^8 $ g）的黑洞主导的时代，该黑洞在原始核合成之前蒸发。在参数空间的重要区域中，这些黑洞将在二元系统中重力结合，并在蒸发之前进行合并。这样的合并导致三个可能可观察到的特征。首先，任何经历过一个或多个合并的黑洞都将具有大量的角动量，从而导致其鹰蒸发，以产生大量的高能吸引力。这些霍金蒸发的产物预计今天将构成热量（$ \ sim $ ev-kev）重力的背景，其能量密度对应于$Δn_{\ rm eff} \ sim 0.01-0.03 $。其次，这些合并将产生高频引力波的随机背景。第三，这些引力波的能量密度可以大于$Δn_{\ rm eff} \ sim 0.3 $，具体取决于合并和蒸发之间的时间长度。这些信号各自可能在未来测量的范围内。
Any abundance of black holes that was present in the early universe will evolve as matter, making up an increasingly large fraction of the total energy density as space expands. This motivates us to consider scenarios in which the early universe included an era that was dominated by low-mass ($M < 5\times 10^8$ g) black holes which evaporate prior to primordial nucleosynthesis. In significant regions of parameter space, these black holes will become gravitationally bound within binary systems, and undergo mergers before evaporating. Such mergers result in three potentially observable signatures. First, any black holes that have undergone one or more mergers will possess substantial angular momentum, causing their Hawking evaporation to produce significant quantities of high-energy gravitons. These products of Hawking evaporation are predicted to constitute a background of hot ($\sim$eV-keV) gravitons today, with an energy density corresponding to $ΔN_{\rm eff} \sim 0.01-0.03$. Second, these mergers will produce a stochastic background of high-frequency gravitational waves. And third, the energy density of these gravitational waves can be as large as $ΔN_{\rm eff} \sim 0.3$, depending on the length of time between the mergers and evaporation. These signals are each potentially within the reach of future measurements.
