Cosmic conundra explained by thermal history and primordial black holes

By B. Carr, S. Clesse, Juan García-Bellido, F. Kühnel. Physics of the Dark Universe, 2019

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A universal mechanism may be responsible for several unresolved cosmic conundra. The sudden drop in the pressure of relativistic matter at $W^{\pm} / Z^{0}$ decoupling, the quark-hadron transition and $e^{+}e^{-}$ annihilation enhances the probability of primordial black hole (PBH) formation in the early Universe. Assuming the amplitude of the primordial curvature fluctuations is approximately scale-invariant, this implies a multi-modal PBH mass spectrum with peaks at $10^{-6}$, $1$, $30$, and $10^{6}\,M_{\odot}$. This suggests a unified PBH scenario which naturally explains the dark matter and recent microlensing observations, the LIGO/Virgo black hole mergers, the correlations in the cosmic infrared and X-ray backgrounds, and the origin of the supermassive black holes in galactic nuclei at high redshift. A distinct prediction of our model is that LIGO/Virgo should soon observe the merging of black holes with masses between $2$ and $5\,M_{\odot}$ or above $70\,M_{\odot}$ and with low mass ratios.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/a8f3200be714ad5d1a629eb3e8b9e1622bba31a0

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Citations in the corpus

Challenges and opportunities of gravitational-wave searches at MHz to GHz frequencies (2020, background): “The boost in primordial BH formation at the time of the QCD transition will induce a peak at the solar mass scale in any primordial BH model with an extended mass function (Byrnes et al. 2018; Carr et al. 2021).”
The exponential tail of inflationary fluctuations: consequences for primordial black holes (2019, background): “arsely distributed, PBHs are of particular cosmological relevance as they could provide seeds for supermassive black-holes in galactic nuclei [20{22], and comprise a large fraction of the dark matter [23,24]. There has been renewed interest in PBHs since the LIGO/VIRGO collaboration reported the rst”
4-OGC: Catalog of Gravitational Waves from Compact Binary Mergers (2021, background): “Other exceptional observations include the high-mass-ratio GW190814 merger (q∼ 9); several proposals exist to explain its formation (Carr et al. 2021; Clesse & Garcia-Bellido 2020; Lu et al. 2020; Olejak et al. 2020; Liu & Lai 2021).”
Primordial Black Holes as Dark Matter: Recent Developments (2020, methodology): “In Section V we discuss how these conundra may have a unified explanation in the scenario proposed in Reference [74].”
Unveiling the gravitational universe at μ-Hz frequencies (2019, background): “and may have arisen due to sudden changes in the relativistic fluid’s radiation pressure, as particles decouple or condense throughout the thermal history of the Universe [70].”
Primordial black holes as dark matter candidates (2021, background): “The threshold is also sensitive to any non-Gaussianity [27–29], the shape of the perturbation profile [30–32] and the equation of state of the medium (a feature exploited in Reference [33]).”