Apparent $w<-1$ and a Lower $S_8$ from Dark Axion and Dark Baryons Interactions

Abstract

We show that a simple coupling between dark energy and dark matter can simultaneously address two distinct hints at new physics coming from cosmological observations. The first is the recent evidence from the DESI project and supernovae observations that the dark energy equation of state~$w$ is evolving over cosmic time from an earlier value that is~$<-1$ to a present-day value~$>-1$. The second observation is the so-called~$S_8$ tension, describing the suppression of the growth of matter overdensities compared to that expected in the~$\Lambda$CDM model. We propose a stable, technically natural particle physics implementation of this idea, in which dark matter consists of dark baryons in a strongly-coupled hidden sector, and the dark energy field is the associated dark axion. The time-variation of the dark matter mass results in an effective dark energy equation of state that exhibits a phantom crossing behavior consistent with recent results. It also results in a slight delay in matter-radiation equality, which suppresses the overall growth of density perturbations.

Match the published version in PRL. Add references and discussions. 10 pages, 6 figures

References in corpus (22)

• Dynamics of dark energy
• Ultralight scalars as cosmological dark matter
• Dark Energy Survey Year 3 Results: Cosmological Constraints from Galaxy Clustering and Weak Lensing
• DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations
• Cosmological Evolution of a Quintom Model of Dark Energy
• Galilean Genesis: an alternative to inflation
• Hyper Suprime-Cam Year 3 Results: Cosmology from Cosmic Shear Power Spectra
• Interacting Dark Energy after DESI Baryon Acoustic Oscillation measurements
• An even lighter QCD axion
• Subluminal Galilean Genesis
• Hints of Nonminimally Coupled Gravity in DESI 2024 Baryon Acoustic Oscillation Measurements
• Consistent lensing and clustering in a low-$S_8$ Universe with BOSS, DES Year 3, HSC Year 1 and KiDS-1000
• Evidence for suppression of structure growth in the concordance cosmological model
• First Constraints on Nuclear Coupling of Axionlike Particles from the Binary Neutron Star Gravitational Wave Event GW170817
• The Early Dark Sector, the Hubble Tension, and the Swampland
• Quantifying the $S_8$ tension and evidence for interacting dark energy from redshift-space distortion measurements
• Sign Switching in Dark Sector Coupling Interactions as a Candidate for Resolving Cosmological Tensions
• Dark QCD Matters
• A Dark Matter Trigger for Early Dark Energy Coincidence
• Cosmological forecasts for future galaxy surveys with the linear point standard ruler: Toward consistent BAO analyses far from a fiducial cosmology
• Hubble tension as a window on the gravitation of the dark matter sector
• Late Time Modification of Structure Growth and the S8 Tension

Cited by in corpus (1)

• Interacting Dark Sectors in light of DESI DR2