Recent numerical simulations of the fragmentation of primordial molecular clouds in hierarchical cosmogonies have suggested that the very first stars (the so-called Population III) may have been rather massive. Here we point out that a numerous population of massive black holes (MBHs) - with masses intermediate between those of stellar and supermassive holes - may be the end product of such an episode of pregalactic star formation. If only one MBH with m(black circle) ≳ 150 M⊙ formed in each of the "minihalos" collapsing at z ≈ 20 from 3 σ fluctuations, then the mass density of Population III MBHs would be comparable to that of the supermassive variety observed in the nuclei of galaxies. Since they form in high-σ rare density peaks, relic MBHs are predicted to cluster in the bulges of present-day galaxies as they become incorporated through a series of mergers into larger and larger systems. Dynamical friction would cause ≳50 (m(black circle)/150 M⊙)1/2 such objects to sink toward the center. The presence of a small cluster of MBHs in galaxy nuclei may have several interesting consequences associated with it, such as tidal captures of ordinary stars (likely followed by disruption), MBH capture by the central supermassive black hole, and gravitational wave radiation from such coalescences. Accreting pregalactic MBHs may be detectable as ultraluminous, off-nuclear X-ray sources.

Madau, P., Rees, M. (2001). Massive Black Holes as Population III Remnants. THE ASTROPHYSICAL JOURNAL, 551(1 Part 2), 27-30 [10.1086/319848].

Massive Black Holes as Population III Remnants

Piero Madau;
2001

Abstract

Recent numerical simulations of the fragmentation of primordial molecular clouds in hierarchical cosmogonies have suggested that the very first stars (the so-called Population III) may have been rather massive. Here we point out that a numerous population of massive black holes (MBHs) - with masses intermediate between those of stellar and supermassive holes - may be the end product of such an episode of pregalactic star formation. If only one MBH with m(black circle) ≳ 150 M⊙ formed in each of the "minihalos" collapsing at z ≈ 20 from 3 σ fluctuations, then the mass density of Population III MBHs would be comparable to that of the supermassive variety observed in the nuclei of galaxies. Since they form in high-σ rare density peaks, relic MBHs are predicted to cluster in the bulges of present-day galaxies as they become incorporated through a series of mergers into larger and larger systems. Dynamical friction would cause ≳50 (m(black circle)/150 M⊙)1/2 such objects to sink toward the center. The presence of a small cluster of MBHs in galaxy nuclei may have several interesting consequences associated with it, such as tidal captures of ordinary stars (likely followed by disruption), MBH capture by the central supermassive black hole, and gravitational wave radiation from such coalescences. Accreting pregalactic MBHs may be detectable as ultraluminous, off-nuclear X-ray sources.
Articolo in rivista - Articolo scientifico
Black hole physics; Cosmology: theory; Early universe; galaxies: formation;
English
2001
551
1 Part 2
27
30
none
Madau, P., Rees, M. (2001). Massive Black Holes as Population III Remnants. THE ASTROPHYSICAL JOURNAL, 551(1 Part 2), 27-30 [10.1086/319848].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/452683
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