The existence of 109 M⊙ supermassive black holes (SMBHs) within the first billion years of the universe remains a puzzle in our conventional understanding of black hole formation and growth. The so-called direct-collapse scenario suggests that the formation of supermassive stars (SMSs) can yield the massive seeds of early SMBHs. This scenario leads to an overly massive BH galaxy (OMBG), whose nuclear black hole’s mass is comparable to or even greater than the surrounding stellar mass: a 104 − 106 M⊙ seed black hole is born in a dark matter halo with a mass as low as 107 − 108 M⊙. The black hole to stellar mass ratio is 𝑀bh/𝑀∗ ≫ 10−3, well in excess of the typical values at lower redshift. We investigate how long these newborn BHs remain outliers in the 𝑀bh − 𝑀∗ relation, by exploring the subsequent evolution of two OMBGs previously identified in the Renaissance simulations. We find that both OMBGs have𝑀bh/𝑀∗>1 during their entire life, from their birth at 𝑧≈15 until they merge with much more massive haloes at 𝑧 ≈ 8. We find that the OMBGs are spatially resolvable from their more massive, 1011 M⊙, neighboring haloes until their mergers are complete at 𝑧 ≈ 8. This affords a window for future observations with JWST and sensitive X-ray telescopes to diagnose the direct-collapse scenario, by detecting similar OMBGs and establishing their uniquely high black hole-to-stellar mass ratio.
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Neutrino point source searches for dark matter spikes
Abstract Any dark matter spikes surrounding black holes in our Galaxy are sites of significant dark matter annihilation, leading to a potentially detectable neutrino signal. In this paper we examine 10 - 10 5 M ⊙ black holes associated with dark matter spikes that formed in early minihalos and still exist in our Milky Way Galaxy today, in light of neutrino data from the ANTARES [1] and IceCube [2] detectors. In various regions of the sky, we determine the minimum distance away from the solar system that a dark matter spike must be in order to have not been detected as a neutrino point source for a variety of representative dark matter annihilation channels. Given these constraints on the distribution of dark matter spikes in the Galaxy, we place significant limits on the formation of the first generation of stars in early minihalos — stronger than previous limits from gamma-ray searches in Fermi Gamma-Ray Space Telescope data. The larger black holes considered in this paper may arise as the remnants of Dark Stars after the dark matter fuel is exhausted; thus neutrino observations may be used to constrain the properties of Dark Stars. The limits are particularly strong for heavier WIMPs. For WIMP masses ∼ 5TeV, we show that ≲ 10 % of minihalos can host first stars that collapse into BHs larger than 10 3 M ⊙ .
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- Award ID(s):
- 2014075
- NSF-PAR ID:
- 10387268
- Date Published:
- Journal Name:
- Journal of Cosmology and Astroparticle Physics
- Volume:
- 2022
- Issue:
- 08
- ISSN:
- 1475-7516
- Page Range / eLocation ID:
- 065
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1088/1475-7516/2022/08/065
