Dark Energy Dynamics in Cosmological Models

Dark energy dynamics underpin the accelerated expansion of the Universe and represent one of the most profound puzzles in contemporary cosmology. In its simplest form, dark energy is modelled as a cosmological constant with a fixed equation of state parameter w = –1, but increasing attention is paid to dynamical alternatives in which w varies with time or redshift. Scalar‐field theories such as quintessence and k-essence introduce a time‐evolving pressure and density, while interacting dark energy scenarios allow energy exchange with dark matter, potentially alleviating the coincidence problem. Observational constraints from type Ia supernovae, baryon acoustic oscillations and measurements of the Hubble parameter H(z) delimit the evolution of dark energy density and pinpoint the redshift at which the Universe transited from deceleration to acceleration. Advances in survey precision, machine-learning methodologies and multi-probe analyses continue to refine limits on w(z), its time derivative and any deviation from a pure cosmological constant, thereby illuminating the nature and origin of dark energy.

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Dark Energy Dynamics in Cosmological Models publication trend

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

Technical terms

Equation of state parameter (w): Ratio of pressure to energy density of dark energy, with w = –1 for a cosmological constant.

Quintessence: Dynamical scalar-field model of dark energy with time-varying w > –1.

Baryon acoustic oscillations (BAO): Regular, periodic fluctuations in matter density used as a standard ruler for cosmic distances.

Sunyaev–Zeldovich effect: Distortion of the cosmic microwave background spectrum by hot electrons in galaxy clusters, employed to infer distances and matter content.

Deceleration–acceleration transition redshift (z_da): The redshift at which the cosmic expansion shifted from slowing under gravity to accelerating under dark energy.

References

1. The Dark Energy Survey: Cosmology Results with ∼1500 New High-redshift Type Ia Supernovae Using the Full 5 yr Data Set. The Astrophysical Journal Letters (2024).
2. Toward Machine-learning-based Metastudies: Applications to Cosmological Parameters. The Astrophysical Journal Supplement Series (2023).
3. Breaking the baryon-dark matter degeneracy in a model-independent way through the Sunyaev-Zeldovich effect. Astronomy & Astrophysics (2024).
4. HUBBLE PARAMETER MEASUREMENT CONSTRAINTS ON THE REDSHIFT OF THE DECELERATION–ACCELERATION TRANSITION, DYNAMICAL DARK ENERGY, AND SPACE CURVATURE. The Astrophysical Journal (2017).