The origin of supermassive black holes at cosmic dawn

Fuente: arXiv
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Autori principali: Sharma, Ritik, Sharma, Mahavir
Natura: Preprint
Pubblicazione: 2023
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author Sharma, Ritik
Sharma, Mahavir
author_facet Sharma, Ritik
Sharma, Mahavir
contents We investigate the steady spherically symmetric accretion in the combined potential of a central black hole and a dark matter halo. For the halo, we consider a Hernquist and an NFW potential and calculate the critical points of the flow. We find that the trans-sonic solution to the centre is not possible without a black hole, whereas two types of trans-sonic solutions are possible in its presence. We also derive the mass accretion rate for a black hole at the centre of a dark matter halo. Our results indicate two phases of accretion. The first is an initial phase with a low accretion rate that depends on the black hole mass, followed by a second phase with a high accretion rate that depends on the halo mass. In the second phase, the black hole mass increases rapidly to supermassive scales, which explains the existence of quasars at redshift $z\ge 6$ and also the recently detected supermassive black holes (SMBHs) by the James Webb Space Telescope (JWST). Further, we calculate the evolution of the Eddington ratio for growing black holes. The accretion is mostly sub-Eddington except for a short super-Eddington episode when the mass accretion rate transitions from low to high. However, during that episode, the black hole mass is likely inadequate to hinder accretion through radiative feedback.
format Preprint
id arxiv_https___arxiv_org_abs_2310_06898
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The origin of supermassive black holes at cosmic dawn
Sharma, Ritik
Sharma, Mahavir
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
We investigate the steady spherically symmetric accretion in the combined potential of a central black hole and a dark matter halo. For the halo, we consider a Hernquist and an NFW potential and calculate the critical points of the flow. We find that the trans-sonic solution to the centre is not possible without a black hole, whereas two types of trans-sonic solutions are possible in its presence. We also derive the mass accretion rate for a black hole at the centre of a dark matter halo. Our results indicate two phases of accretion. The first is an initial phase with a low accretion rate that depends on the black hole mass, followed by a second phase with a high accretion rate that depends on the halo mass. In the second phase, the black hole mass increases rapidly to supermassive scales, which explains the existence of quasars at redshift $z\ge 6$ and also the recently detected supermassive black holes (SMBHs) by the James Webb Space Telescope (JWST). Further, we calculate the evolution of the Eddington ratio for growing black holes. The accretion is mostly sub-Eddington except for a short super-Eddington episode when the mass accretion rate transitions from low to high. However, during that episode, the black hole mass is likely inadequate to hinder accretion through radiative feedback.
title The origin of supermassive black holes at cosmic dawn
topic Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2310.06898