Cosmology of self-interacting ultralight dark matter: simultaneous shifts in the Hubble constant and structure growth
Abstract
We study the cosmology of self-interacting ultralight dark matter. The scalar field evolves from an early Hubble-frozen phase to a quartic-dominated radiation-like phase and finally to a quadratic matter-like phase. The intermediate phase increases the pre-recombination expansion rate and reduces the sound horizon, while the late phase allows the same field to contribute to dark matter. We implement the background and linear perturbations of a mixed cold-dark-matter and ultralight-dark-matter cosmology in CLASS. For m=10−22 eV and m̃≃1 eV, increasing the ultralight-dark-matter fraction raises the fixed-θ* value of H0, lowers the late-time clustering amplitude, strengthens the scale-dependent matter-power suppression, and produces a smooth CMB-temperature residual reaching about 9% for the largest fraction considered. The model therefore generates simultaneous background and growth shifts in the directions relevant to the Hubble and structure-growth tensions. Establishing whether these shifts improve a joint fit requires a likelihood-level observational analysis.
Related
- Quantum corrections as a Bound for Detecting Self-Interacting Ultralight Dark Matter
- Four-Sector Cosmology (FSC): A Complex Dark Energy Field, Spontaneous Symmetry Breaking, and the Origin of the Cosmological Constant from Observed Matter Asymmetry δ = 0.2%
- Constraints on interacting dark energy with a constant equation of state in light of DESI DR2: The role of the interaction term
- Introducing the GION Lightcone Simulation Suite for Multi-Wavelength Large-Scale Structure Cosmology
- Searching for signatures of self-interacting dark matter in halos from full physics simulations: From 3D structure to projected observables
BibTeX
@misc{lee2026cosmology,
title = {{Cosmology of self-interacting ultralight dark matter: simultaneous shifts in the Hubble constant and structure growth}},
author = {Seokcheon Lee and Jae-Weon Lee},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.29582},
eprint = {2610.29582},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.29582},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Cosmology of self-interacting ultralight dark matter: simultaneous shifts in the Hubble constant and structure growth
AU - Seokcheon Lee
AU - Jae-Weon Lee
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2610.29582
UR - https://arxiv.org/abs/2610.29582
AB - We study the cosmology of self-interacting ultralight dark matter. The scalar field evolves from an early Hubble-frozen phase to a quartic-dominated radiation-like phase and finally to a quadratic matter-like phase. The intermediate phase increases the pre-recombination expansion rate and reduces the sound horizon, while the late phase allows the same field to contribute to dark matter. We implement the background and linear perturbations of a mixed cold-dark-matter and ultralight-dark-matter cosmology in CLASS. For m=10^−22 eV and m̃≃1 eV, increasing the ultralight-dark-matter fraction raises the fixed-θ_* value of H_0, lowers the late-time clustering amplitude, strengthens the scale-dependent matter-power suppression, and produces a smooth CMB-temperature residual reaching about 9% for the largest fraction considered. The model therefore generates simultaneous background and growth shifts in the directions relevant to the Hubble and structure-growth tensions. Establishing whether these shifts improve a joint fit requires a likelihood-level observational analysis.
ER -