Phenomenological Note: Could Growing Dark Matter Mimic the Apparent Weakening of Dark Energy? A Critical Look at DESI DR2 Results

This phenomenological note critically examines the recent DESI DR2 preference for dynamical dark energy with w0 ~ -0.7 and wa ~ -1.0. We argue that an apparent weakening of dark energy at low redshift could be mimicked by growing dark matter or interacting dark sector models, rather than a true phantom crossing. Using the CPL parameterization w(a) = w0 + wa(1-a), we discuss how growth of structure and background expansion degeneracies can lead to misinterpretation of DESI results. We call for joint analysis with growth rate data to break the degeneracy.

Keywords: Dark Energy, DESI, Growing Dark Matter, CPL, Cosmology

ORCID: 0009-0008-9786-4695
Independent Researcher, Basra, Iraq