Speaker
Description
Dynamical Dark Energy with Dark Sector Interactions: A Combined Fluid Approach to the Hubble Tension
The Dark Energy Spectroscopic Instrument (DESI) results have shown a strong
preference for a dynamical dark energy background. The discrepancy between
early- and late-time Hubble measurements, known as the Hubble tension, plagues
the concordance ΛCDM model.
In this work, we explore phenomenological fluid models of dark sector interactions
in both a dynamical dark energy background (w₀ wₐ) and a constant equation of
state, to investigate whether these models are consistent with DESI's preference
for evolving dark energy while simultaneously alleviating the Hubble tension.
We use the CPL form, w( a) = w₀ + wₐ(1−a), to parametrize the dark energy
equation of state and introduce dark sector interactions through an interaction
term Q in the continuity equations. We consider three Q forms: proportional to
dark energy density, Q = 3 Hξρde; dark matter density,
Q = 3 Hξρdm; and total dark sector density,
Q = 3 Hξ(ρde + ρdm). Each model is run against both
the dynamical w₀ wₐ background and a constant equation of state.
We perform Boltzmann and Markov Chain Monte Carlo (MCMC) analyses, with
likelihoods drawn from Planck CMB, DESI BAO, and Type Ia supernovae datasets.
For each Q form, constraints on (w₀, wₐ, ξ) are derived to examine the
extent to which the extended parameter space shifts the inferred value of
H₀, providing a systematic model comparison across interaction choices.
We will present the resulting constraints and discuss their implications for
the Hubble tension and DESI compatibility.
| Parallel session | Astrophysical Probes of Dark Matter and Dark Energy |
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