Clustering of primordial black holes formed in a matter-dominated epoch. (arXiv:1909.04053v1 [astro-ph.CO])

<a href="http://arxiv.org/find/astro-ph/1/au:+Matsubara_T/0/1/0/all/0/1">Takahiko Matsubara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Terada_T/0/1/0/all/0/1">Takahiro Terada</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kohri_K/0/1/0/all/0/1">Kazunori Kohri</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yokoyama_S/0/1/0/all/0/1">Shuichiro Yokoyama</a>

In the presence of the local-type primordial non-Gaussianity, it is known

that the clustering of primordial black holes (PBHs) emerges even on

super-horizon scales at the formation time. This effect has been investigated

in the high-peak limit of the PBH formation in the radiation-dominated epoch in

the literature. There is another possibility that the PBH formation takes place

in the early matter-dominated epoch. In this scenario, the high-peak limit is

not applicable because even initially small perturbations grow and can become a

PBH. We first derive a general formula to estimate the clustering of PBHs with

primordial non-Gaussianity without assuming the high-peak limit, and then apply

this formula to a model of PBH formation in a matter-dominated epoch.

Clustering is less significant in the case of the PBH formation in the

matter-dominated epoch than that in the radiation-dominated epoch.

Nevertheless, it is much larger than the Poisson shot noise in many cases.

Relations to the constraints of the isocurvature perturbations by the cosmic

microwave background radiation are quantitatively discussed.

In the presence of the local-type primordial non-Gaussianity, it is known

that the clustering of primordial black holes (PBHs) emerges even on

super-horizon scales at the formation time. This effect has been investigated

in the high-peak limit of the PBH formation in the radiation-dominated epoch in

the literature. There is another possibility that the PBH formation takes place

in the early matter-dominated epoch. In this scenario, the high-peak limit is

not applicable because even initially small perturbations grow and can become a

PBH. We first derive a general formula to estimate the clustering of PBHs with

primordial non-Gaussianity without assuming the high-peak limit, and then apply

this formula to a model of PBH formation in a matter-dominated epoch.

Clustering is less significant in the case of the PBH formation in the

matter-dominated epoch than that in the radiation-dominated epoch.

Nevertheless, it is much larger than the Poisson shot noise in many cases.

Relations to the constraints of the isocurvature perturbations by the cosmic

microwave background radiation are quantitatively discussed.

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