A Constrained Dynamical Dark Energy Parameterization with Linked w₀ and wₐ
Internal ID: CGI-RSR-000001
Document Type: Research Paper
Publication Date: April 2026
Status: Public
Domains: Physics
Research Topics: Dark Energy, Cosmological Constant, DESI
Abstract
We present a constrained dynamical dark-energy parameterization that provides a fit-ready alternative to standard phenomenological models used in late-time cosmology. At the level of the expansion history, the model introduces a minimal modification to ΛCDM that can be implemented directly in H(z), BAO, and distance–redshift analyses. The parameterization is motivated by a relaxation process toward a late-time locked state and yields a curved equation of state w(z) that approaches −1 asymptotically while allowing mild intermediate-redshift departures. Unlike the standard Chevallier–Polarski–Linder (CPL) ansatz, in which (w0,wa) are treated as independent, the present model links them through a single underlying dynamical structure, restricting the allowed region of parameter space. We derive the corresponding expansion history, summarize the associated observables, and compare the model to CPL over the observed redshift range. The resulting framework provides a reduced-degree-of-freedom description of dark-energy evolution that can be tested directly against large-scale structure data.
Available Document
Citation:
Petersen, B. L., & Johnson, R. K. (2026). A Constrained Dynamical Dark Energy Parameterization with Linked w_0 and w_a. Zenodo. https://doi.org/10.5281/zenodo.19650923
Source Code and Supporting Materials
H_residual_tuned.pdf
H_residual_tuned.png
w_fit_relaxation.png
Summary and Notes
Document provided as a directed note to help researchers in the field.
Related Work
Foundations of CG Textbook