Primordial black holes may encode the conditions of the early universe, and may even constitute a significant fraction of cosmological dark matter. Their existence has yet to be established. However, black holes with masses below $\sim1~\mathrm{M}_\odot$ cannot form as an endpoint of stellar evolution, so the detection of even one such object would be a smoking gun for new physics, and would constitute evidence that at least a fraction of the dark matter consists of primordial black holes. Gravitational wave detectors are capable of making a definitive discovery of this kind by detecting mergers of light black holes. But since the merger rate depends strongly on the shape of the black hole mass function, it is difficult to determine the potential for discovery or constraint as a function of the overall abundance of black holes. Here, we directly maximize and minimize the merger rate to connect observational results to the actual abundance of observable objects. We show that LIGO can discover mergers of light primordial black holes within the next decade even if such black holes constitute only a very small fraction of dark matter. A single merger event involving such an object would (i) provide conclusive evidence of new physics, (ii) establish the nature of some fraction of dark matter, and (iii) probe cosmological history at scales far beyond those observable today.

中文翻译：

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LIGO 原始黑洞的独立模型发现前景

原始黑洞可能编码了早期宇宙的条件，甚至可能构成宇宙暗物质的重要组成部分。它们的存在尚未确定。然而，质量低于 $\sim1~\mathrm{M}_\odot$ 的黑洞不能作为恒星演化的终点而形成，因此，即使探测到一个这样的物体也将成为新物理学的吸烟枪，并将构成证据至少有一部分暗物质由原始黑洞组成。引力波探测器能够通过探测轻黑洞的合并来确定这种类型的发现。但由于合并率在很大程度上取决于黑洞质量函数的形状，因此很难确定发现或约束作为黑洞整体丰度的函数的潜力。这里，我们直接最大化和最小化合并率，以将观测结果与可观测对象的实际丰度联系起来。我们表明 LIGO 可以在未来十年内发现轻原始黑洞的合并，即使这些黑洞只占暗物质的很小一部分。涉及这样一个物体的单一合并事件将（i）提供新物理学的确凿证据，（ii）确定暗物质部分的性质，以及（iii）在远远超出今天可观察到的尺度上探索宇宙学历史。