Dynamical Models of Dark Energy in Cosmology

The discovery that the expansion of the Universe is accelerating has led to a rich landscape of theoretical frameworks in which the dark energy component evolves in time, rather than remaining a fixed cosmological constant. Dynamical models introduce scalar fields or composite fluids whose energy density and pressure vary with cosmic epoch, thereby affecting the growth of structure and offering potential relief to observational tensions in measurements of the Hubble constant and the amplitude of matter clustering. Quintessence models posit a slowly rolling scalar field, while phantom‐type scenarios allow the equation of state to drop below –1, often invoking nonstandard kinetic terms. Alternative approaches derive a mild time dependence of vacuum energy through quantum field theory in an expanding spacetime, leading to so-called running vacuum models. Composite constructions combine distinct dark energy components that dominate in succession, and interactions with dark matter have also been explored. These dynamical frameworks are tested against supernova luminosity distances, baryon acoustic oscillation scales, cosmic microwave background anisotropies and large‐scale structure surveys, revealing that even a small deviation from a rigid cosmological constant can improve consistency across datasets and shed light on the fundamental nature of the dark sector.

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Dynamical Models of Dark Energy in Cosmology publication trend

The graph below shows the total number of articles in dynamical models of dark energy in cosmology across all publications each year (not limited to Nature Index journals).

Technical terms

Dark energy: A form of energy with negative pressure responsible for the observed accelerated expansion of the Universe.

Equation of state: The ratio of pressure to energy density (w), which for dark energy determines its influence on cosmic expansion.

Quintessence: A dynamical scalar field model of dark energy with −1

Phantom energy: A hypothetical field with w<−1 that leads to super‐accelerated expansion and unusual energy conditions.

Running vacuum model (RVM): A framework in which the vacuum energy density varies as a function of the Hubble parameter and its derivatives.

Baryon acoustic oscillations (BAO): Regular, periodic fluctuations in the density of visible baryonic matter in the Universe, used as a standard ruler in cosmology.

Hubble parameter (H): The rate of expansion of the Universe at a given time, defined as the time derivative of the scale factor divided by the scale factor itself.

Cosmological constant (Λ): A constant term in Einstein’s equations representing a rigid vacuum energy density with w=−1.

References

1. Composite dark energy and the cosmological tensions. Physics Letters B (2025).
2. Fitting the DESI BAO data with dark energy driven by the Cohen-Kaplan-Nelson bound. Journal of Cosmology and Astroparticle Physics (2024).
3. Running vacuum in QFT in FLRW spacetime: the dynamics of ρvac(H) from the quantized matter fields. European Physical Journal C (2023).