Toward alleviating the 𝐻₀ and 𝑆₈ tensions with early dark energy-dark matter drag

Authors

T. Simon
T. Adi
J. L. Bernal
E. D. Kovetz
V. Poulin
Tristan L. Smith, Swarthmore CollegeFollow

Document Type

Article

Publication Date

1-13-2025

Published In

Physical Review D

Abstract

Early dark energy, an additional component of dark energy active in the decade of redshift before recombination, has emerged as one of the most effective models at reducing the “𝐻₀ tension” between direct measurement of the Hubble parameter 𝐻₀ in the late Universe and the Λ CDM prediction when calibrated on Planck. However, it requires a slight increase in the dark matter density 𝜔_cdm and primordial tilt 𝑛_𝑠 that worsens the “𝑆₈ tension” between measurements of weak gravitational lensing at low redshifts and the Planck/Λ⁢CDM prediction. Using a phenomenological fluid model, we investigate whether the inclusion of a drag term between dark matter and early dark energy can compensate for the effect of the increase in power at small-scales, such that both 𝐻₀ and 𝑆₈ tensions are simultaneously alleviated. We find that this works if the drag term is dynamically relevant in the post-recombination universe. However, a drag term active before or just around the time at which the early dark energy contribution to the energy density is maximum is significantly constrained due to its impact on the matter perturbations before recombination, and the subsequent modifications to the cosmic microwave background power spectra.

Comments

This work is freely available courtesy of the American Physical Society.

Recommended Citation

T. Simon et al. (2025). "Toward alleviating the 𝐻₀ and 𝑆₈ tensions with early dark energy-dark matter drag". Physical Review D. Volume 111, DOI: 10.1103/PhysRevD.111.023523
https://works.swarthmore.edu/fac-physics/564