Formation and Evolution of Primordial Black Hole Binaries in the Early Universe
| Autor: | Christian Spethmann, Martti Raidal, Hardi Veermäe, Ville Vaskonen |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Astrophysics and Astronomy
Cosmology and Nongalactic Astrophysics (astro-ph.CO) media_common.quotation_subject Dark matter Binary number FOS: Physical sciences Primordial black hole Astrophysics 01 natural sciences High Energy Physics - Phenomenology (hep-ph) 0103 physical sciences Particle Physics - Phenomenology media_common astro-ph.HE Physics High Energy Astrophysical Phenomena (astro-ph.HE) 010308 nuclear & particles physics Gravitational wave Order (ring theory) hep-ph Astronomy and Astrophysics Comoving distance LIGO Universe High Energy Physics - Phenomenology astro-ph.CO Astrophysics - High Energy Astrophysical Phenomena Astrophysics - Cosmology and Nongalactic Astrophysics |
| DOI: | 10.48550/arxiv.1812.01930 |
| Popis: | The abundance of primordial black holes (PBHs) in the mass range $0.1 - 10^3 M_\odot$ can potentially be tested by gravitational wave observations due to the large merger rate of PBH binaries formed in the early universe. To put the estimates of the latter on a firmer footing, we first derive analytical PBH merger rate for general PBH mass functions while imposing a minimal initial comoving distance between the binary and the PBH nearest to it, in order to pick only initial configurations where the binary would not get disrupted. We then study the formation and evolution of PBH binaries before recombination by performing N-body simulations. We find that the analytical estimate based on the tidally perturbed 2-body system strongly overestimates the present merger rate when PBHs comprise all dark matter, as most initial binaries are disrupted by the surrounding PBHs. This is mostly due to the formation of compact N-body systems at matter-radiation equality. However, if PBHs make up a small fraction of the dark matter, $f_{\rm PBH} \lesssim 10\%$, these estimates become more reliable. In that case, the merger rate observed by LIGO imposes the strongest constraint on the PBH abundance in the mass range $2 - 160 M_\odot$. Finally, we argue that, even if most initial PBH binaries are perturbed, the present BH-BH merger rate of binaries formed in the early universe is larger than $\mathcal{O}(10)\,{\rm Gpc}^{-3} {\rm yr}^{-1}\, f_{\rm PBH}^3$ Comment: 32pages, 12 figures, typos corrected, references added, figures updated, matches version published in JCAP |
| Databáze: | OpenAIRE |
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