Not-quite-primordial black holes

Fuente: arXiv
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Autori principali: Qin, Wenzer, Kumar, Soubhik, Natarajan, Priyamvada, Weiner, Neal
Natura: Preprint
Pubblicazione: 2025
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author Qin, Wenzer
Kumar, Soubhik
Natarajan, Priyamvada
Weiner, Neal
author_facet Qin, Wenzer
Kumar, Soubhik
Natarajan, Priyamvada
Weiner, Neal
contents We propose a new mechanism for the formation of seeds of supermassive black holes at early cosmic epochs. Enhanced density fluctuations with amplitudes that are not large enough to form primordial black holes post-inflation can still lead to collapsed dark matter halos at very early times. For halos forming prior to $1+z \approx 200$, the Cosmic Microwave Background (CMB) is energetic enough to suppress the formation of molecular hydrogen, hence preventing cooling and fragmentation, as a consequence of which baryons falling into the potential well of the halo may undergo "direct collapse" into a black hole. We show using a few illustrative models how this mechanism may account for the abundance of high-redshift black holes inferred from observations by the James Webb Space Telescope while remaining consistent with current limits from CMB spectral distortions. Limits on the primordial power spectrum are also derived by requiring that the universe not reionize too early.
format Preprint
id arxiv_https___arxiv_org_abs_2506_13858
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Not-quite-primordial black holes
Qin, Wenzer
Kumar, Soubhik
Natarajan, Priyamvada
Weiner, Neal
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
High Energy Physics - Phenomenology
We propose a new mechanism for the formation of seeds of supermassive black holes at early cosmic epochs. Enhanced density fluctuations with amplitudes that are not large enough to form primordial black holes post-inflation can still lead to collapsed dark matter halos at very early times. For halos forming prior to $1+z \approx 200$, the Cosmic Microwave Background (CMB) is energetic enough to suppress the formation of molecular hydrogen, hence preventing cooling and fragmentation, as a consequence of which baryons falling into the potential well of the halo may undergo "direct collapse" into a black hole. We show using a few illustrative models how this mechanism may account for the abundance of high-redshift black holes inferred from observations by the James Webb Space Telescope while remaining consistent with current limits from CMB spectral distortions. Limits on the primordial power spectrum are also derived by requiring that the universe not reionize too early.
title Not-quite-primordial black holes
topic Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2506.13858