Superhorizon Isocurvature as a Window into Dark Matter Production

Fuente: arXiv
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Autori principali: Gerlach, Christopher, Ratzinger, Wolfram, Schwaller, Pedro
Natura: Preprint
Pubblicazione: 2025
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author Gerlach, Christopher
Ratzinger, Wolfram
Schwaller, Pedro
author_facet Gerlach, Christopher
Ratzinger, Wolfram
Schwaller, Pedro
contents In the presence of primordial isocurvature perturbations, for example in a separate dark radiation sector, the superhorizon evolution of curvature perturbations becomes nontrivial. If the dark sector is radiation-like and constitutes a significant fraction of the energy density, its isocurvature can imply isocurvature in the inflaton sector even without direct interactions between the sectors. In this article, we revisit superhorizon curvature and isocurvature evolution in the long-wavelength limit systematically, drawing a simple picture of how to understand the nature of these fluctuations from first principles and without brute-force cosmic perturbation theory. We show how the described setup is able to source isocurvature in simple models of dark matter such as freeze-in and freeze-out and demonstrate that future measurements of matter and neutrino isocurvature can potentially discriminate between these two mechanisms.
format Preprint
id arxiv_https___arxiv_org_abs_2510_21917
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Superhorizon Isocurvature as a Window into Dark Matter Production
Gerlach, Christopher
Ratzinger, Wolfram
Schwaller, Pedro
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
In the presence of primordial isocurvature perturbations, for example in a separate dark radiation sector, the superhorizon evolution of curvature perturbations becomes nontrivial. If the dark sector is radiation-like and constitutes a significant fraction of the energy density, its isocurvature can imply isocurvature in the inflaton sector even without direct interactions between the sectors. In this article, we revisit superhorizon curvature and isocurvature evolution in the long-wavelength limit systematically, drawing a simple picture of how to understand the nature of these fluctuations from first principles and without brute-force cosmic perturbation theory. We show how the described setup is able to source isocurvature in simple models of dark matter such as freeze-in and freeze-out and demonstrate that future measurements of matter and neutrino isocurvature can potentially discriminate between these two mechanisms.
title Superhorizon Isocurvature as a Window into Dark Matter Production
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2510.21917