Germani Cristiano, Musco Ilia
Departement de Física Quàntica i Astrofisica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.
Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.
Phys Rev Lett. 2019 Apr 12;122(14):141302. doi: 10.1103/PhysRevLett.122.141302.
In this Letter, combining peak theory and the numerical analysis of gravitational collapse in the radiation dominated era, we show that the abundance of primordial blacks holes, generated by an enhancement in the inflationary power spectrum, is extremely dependent on the shape of the peak. Given the amplitude of the power spectrum, we show that the density of primordial black holes generated from a narrow peak is exponentially smaller than in the case of a broad peak. Specifically, for a top-hat profile of the power spectrum in Fourier space, we find that to have primordial black holes comprising all of the dark matter, one would only need a power spectrum amplitude an order of magnitude smaller than suggested previously, whereas in the case of a narrow peak, one would instead need a much larger power spectrum amplitude, which in many cases would invalidate the perturbative analysis of cosmological perturbations. Finally, we show that, although critical collapse gives a broad mass spectrum, the density of primordial black holes formed is dominated by masses roughly equal to the cosmological horizon mass measured at horizon crossing.
在这篇快报中，结合峰值理论以及辐射主导时期引力坍缩的数值分析，我们表明，由暴胀功率谱增强产生的原初黑洞丰度极其依赖于峰值的形状。给定功率谱的幅度，我们表明，由窄峰产生的原初黑洞密度比宽峰情况呈指数级小。具体而言，对于傅里叶空间中功率谱的平顶分布，我们发现，要使原初黑洞构成所有暗物质，所需的功率谱幅度仅比先前建议的小一个数量级，而在窄峰情况下，则需要大得多的功率谱幅度，这在许多情况下会使宇宙学微扰的微扰分析无效。最后，我们表明，尽管临界坍缩给出了一个宽泛的质量谱，但形成的原初黑洞密度主要由大致等于视界穿越时所测宇宙学视界质量的质量主导。
