A universal bound on the duration of a kination era
High Energy Physics - Phenomenology
2026-01-12 v2 Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
Abstract
We show that primordial adiabatic curvature fluctuations generate an instability of the scalar field sourcing a kination era. We demonstrate that the generated higher Fourier modes constitute a radiation-like component dominating over the kination background after about e-folds of cosmic expansion. Current constraints on the extra number of neutrino flavors thus imply the observational bound of approximately 10 e-folds, representing the most stringent bound to date on the stiffness of the equation of state of the pre-Big-Bang-Nucleosynthesis universe.
Keywords
Cite
@article{arxiv.2501.17226,
title = {A universal bound on the duration of a kination era},
author = {Cem Eröncel and Yann Gouttenoire and Ryosuke Sato and Géraldine Servant and Peera Simakachorn},
journal= {arXiv preprint arXiv:2501.17226},
year = {2026}
}
Comments
5 pages, 2 figures + appendix (10 pages). Published in PRL