Stochastic gravitational waves associated with the formation of primordial black holes

By T. Nakama, J. Silk, M. Kamionkowski. 2016

181 citations recorded by the source corpus.

Primordial black hole (PBH) mergers have been proposed as an explanation for the gravitational wave events detected by the LIGO collaboration. Such PBHs may be formed in the early Universe as a result of the collapse of extremely rare high-sigma peaks of primordial fluctuations on small scales, as long as the amplitude of primordial perturbations on small scales is enhanced significantly relative to the amplitude of perturbations observed on large scales. One consequence of these small-scale perturbations is generation of stochastic gravitational waves that arise at second order in scalar perturbations, mostly before the formation of the PBHs. These induced gravitational waves have been shown, assuming gaussian initial conditions, to be comparable to the current limits from the European Pulsar Timing Array, severely restricting this scenario. We show, however, that models with enhanced fluctuation amplitudes typically involve non-gaussian initial conditions. With such initial conditions, the current limits from pulsar timing can be evaded. The amplitude of the induced gravitational-wave background can be larger or smaller than the stochastic gravitational-wave background from supermassive black hole binaries.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/8c03fa0ceda3a7f4a789c489ebb3d25d9d9c5d7b

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In Astronomy and Astrophysics

1. Juan García-Bellido
2. B. Carr
3. Florian Kuhnel
4. C. Byrnes
5. Marco Peloso
6. S. Young
7. V. Vaskonen
8. C. Unal

Citations in the corpus

• Solar-mass primordial black holes explain NANOGrav hint of gravitational waves (2020, unknown): “It also affects the second-order GWs [125–129].”
• Challenges and opportunities of gravitational-wave searches at MHz to GHz frequencies (2020, background): “The precise amount of produced GWs depends on the statistics of the scalar perturbations (Nakama et al. 2017; Garcı́a-Bellido et al. 2017; Cai et al. 2019; Unal 2019).”
• Primordial black hole formation and abundance: contribution from the non-linear relation between the density and curvature perturbation (2019, methodology): “8 × 1017M (using the same parameters as [60]).”
• Gravitational wave signatures of inflationary models from Primordial Black Hole dark matter (2017, background): “Our numerical value 20 is about 18% greater than the one of [38] since we are taking Ωradh 2 ' 4.”
• Primordial black holes with an accurate QCD equation of state (2018, methodology): “[38]) The fraction βeq represents the abundance at the time of matterradiation equality of PBHs which formed at a given earlier time - in order to calculate the total abundance of PBHs, ΩPBH, it is necessary to integrate βeq over all times at which PBHs form,”
• Mechanisms for primordial black hole production in string theory (2018, methodology): “q) 1=2 g s(T eq) g s(T f) 2=3 k eq k 2 ’1:6 1018 g 0:2 g (T f) 106:75 1=6 k 5:5 1310 Mpc 1 2 ; (3.15) where in the second line we assumed g (T) = g s(T) and used MH eq ’5:6 1050g [51], g (T eq) = 3:38, k eq = 0:07 mh2 Mpc 1. The value of the constant of proportionality 18 = 0:2 is suggeste”
• Gravitational waves induced by scalar perturbations during a gradual transition from an early matter era to the radiation era (2019, unknown): “[11, 14, 24, 29].”
• Non-Gaussianity and the induced gravitational wave background (2021, unknown): “In this work we revisit the problem of GW backgrounds induced by non-Gaussian curvature perturbations [50, 51, 60, 66, 74, 86, 88, 110].”
• Two populations of LIGO-Virgo black holes (2020, background): “First, slightly before the matter-radiation equality close PBH pairs decouple from the Hubble flow and form binaries [8, 11, 12, 14, 17, 47–50].”