The silent dark sector: a field-theory approach to unified dark fluids with vanishing speed of sound

2026/07/21 by Javier de Cruz Pérez, Darío Jaramillo-Garrido, Antonio L. Maroto +1
#astro-ph.CO #gr-qc

paper · pdf

Abstract

We introduce a novel class of field-theory models that provide a unified description of the dark sector as a single perfect fluid with vanishing sound speed. These models also admit the interpretation of cold dark matter interacting with vacuum energy while avoiding any phantom behavior and including standard ΛCDM as a particular case. Built upon a single scalar field invariant under transverse diffeomorphisms, the framework naturally implements the constraints imposed in the so called mimetic models. We analyze a particular simple example exhibiting an effectively evolving dark energy and find that it can reproduce the DESI best-fit CPL evolution with the same number of free parameters.

Citations

• The Dark Energy Survey supernova program: a reanalysis of cosmology results and evidence for evolving dark energy with an updated Type Ia supernova calibration
• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• Dark matter and dark energy interactions: theoretical challenges, cosmological implications and observational signatures

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