Halo Formation from Yukawa Forces in the Very Early Universe

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Main Authors: Domènech, Guillem, Inman, Derek, Kusenko, Alexander, Sasaki, Misao
Format: Preprint
Published: 2023
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author Domènech, Guillem
Inman, Derek
Kusenko, Alexander
Sasaki, Misao
author_facet Domènech, Guillem
Inman, Derek
Kusenko, Alexander
Sasaki, Misao
contents If long-range attractive forces exist and are stronger than gravity then cosmic halo formation can begin in the radiation-dominated era. We study a simple realization of this effect in a system where dark matter fermions have Yukawa interactions mediated by scalar particles, analogous to the Higgs boson in the standard model. We develop a self-consistent description of the system including exact background dynamics of the scalar field, and precise modelling of the fermion density fluctuations. For the latter, we provide accurate approximations for the linear growth as well as quantitative modelling of the nonlinear evolution using N-body simulations. We find that halo formation occurs exponentially fast and on scales substantially larger than simple estimates predict. The final fate of these halos remains uncertain, but could be annihilation, dark stars, primordial black holes, or even the existence of galaxy-sized halos at matter-radiation equality. More generally, our results demonstrate the importance of mapping scalar-mediated interactions onto structure formation outcomes and constraints for beyond the standard model theories.
format Preprint
id arxiv_https___arxiv_org_abs_2304_13053
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Halo Formation from Yukawa Forces in the Very Early Universe
Domènech, Guillem
Inman, Derek
Kusenko, Alexander
Sasaki, Misao
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
High Energy Physics - Theory
If long-range attractive forces exist and are stronger than gravity then cosmic halo formation can begin in the radiation-dominated era. We study a simple realization of this effect in a system where dark matter fermions have Yukawa interactions mediated by scalar particles, analogous to the Higgs boson in the standard model. We develop a self-consistent description of the system including exact background dynamics of the scalar field, and precise modelling of the fermion density fluctuations. For the latter, we provide accurate approximations for the linear growth as well as quantitative modelling of the nonlinear evolution using N-body simulations. We find that halo formation occurs exponentially fast and on scales substantially larger than simple estimates predict. The final fate of these halos remains uncertain, but could be annihilation, dark stars, primordial black holes, or even the existence of galaxy-sized halos at matter-radiation equality. More generally, our results demonstrate the importance of mapping scalar-mediated interactions onto structure formation outcomes and constraints for beyond the standard model theories.
title Halo Formation from Yukawa Forces in the Very Early Universe
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
High Energy Physics - Theory
url https://arxiv.org/abs/2304.13053