Gravitational Wave and CMB Probes of Axion Kination

Fuente: arXiv
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Auteurs principaux: Co, Raymond T., Dunsky, David, Fernandez, Nicolas, Ghalsasi, Akshay, Hall, Lawrence J., Harigaya, Keisuke, Shelton, Jessie
Format: Preprint
Publié: 2021
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author Co, Raymond T.
Dunsky, David
Fernandez, Nicolas
Ghalsasi, Akshay
Hall, Lawrence J.
Harigaya, Keisuke
Shelton, Jessie
author_facet Co, Raymond T.
Dunsky, David
Fernandez, Nicolas
Ghalsasi, Akshay
Hall, Lawrence J.
Harigaya, Keisuke
Shelton, Jessie
contents Rotations of an axion field in field space provide a natural origin for an era of kination domination, where the energy density is dominated by the kinetic term of the axion field, preceded by an early era of matter domination. Remarkably, no entropy is produced at the end of matter domination and hence these eras of matter and kination domination may occur even after Big Bang Nucleosynthesis. We derive constraints on these eras from both the cosmic microwave background and Big Bang Nucleosynthesis. We investigate how this cosmological scenario affects the spectrum of possible primordial gravitational waves and find that the spectrum features a triangular peak. We discuss how future observations of gravitational waves can probe the viable parameter space, including regions that produce axion dark matter by the kinetic misalignment mechanism or the baryon asymmetry by axiogenesis. For QCD axion dark matter produced by the kinetic misalignment mechanism, a modification to the inflationary gravitational wave spectrum occurs above 0.01 Hz and, for high values of the energy scale of inflation, the prospects for discovery are good. We briefly comment on implications for structure formation of the universe.
format Preprint
id arxiv_https___arxiv_org_abs_2108_09299
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Gravitational Wave and CMB Probes of Axion Kination
Co, Raymond T.
Dunsky, David
Fernandez, Nicolas
Ghalsasi, Akshay
Hall, Lawrence J.
Harigaya, Keisuke
Shelton, Jessie
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
Rotations of an axion field in field space provide a natural origin for an era of kination domination, where the energy density is dominated by the kinetic term of the axion field, preceded by an early era of matter domination. Remarkably, no entropy is produced at the end of matter domination and hence these eras of matter and kination domination may occur even after Big Bang Nucleosynthesis. We derive constraints on these eras from both the cosmic microwave background and Big Bang Nucleosynthesis. We investigate how this cosmological scenario affects the spectrum of possible primordial gravitational waves and find that the spectrum features a triangular peak. We discuss how future observations of gravitational waves can probe the viable parameter space, including regions that produce axion dark matter by the kinetic misalignment mechanism or the baryon asymmetry by axiogenesis. For QCD axion dark matter produced by the kinetic misalignment mechanism, a modification to the inflationary gravitational wave spectrum occurs above 0.01 Hz and, for high values of the energy scale of inflation, the prospects for discovery are good. We briefly comment on implications for structure formation of the universe.
title Gravitational Wave and CMB Probes of Axion Kination
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2108.09299