2025/09/14 by Antonio Pasqua, Pasqua, Antonio
Earth and Planetary Sciences · Physics and Astronomy · #Cosmology and Gravitation Theories #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Geophysics and Gravity Measurements #Relativity and Gravitational Theory
paper · pdf · doi:10.48550/arxiv.2509.12284
openalex publication_date 2025/09/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In this work, we investigate two Dark Energy (DE) models characterized by higher-order derivatives of the Hubble parameter H, which generalize previously proposed DE scenarios. Assuming a power-law form of the scale factor a(t) given by a(t)=b0tn, we derive analytical expressions for the DE energy density, pressure, the Equation of State (EoS) parameter, the deceleration parameter and the evolutionary form of the fractional DE density. Both non-interacting and interacting dark sector frameworks are examined, with the interaction modeled through a coupling term proportional to the Dark Matter (DM) energy density. For specific parameter sets corresponding to power-law indices n=2, n=3, and n=4, we compute the present age of the Universe. The values obtained slightly deviate from the observationally inferred age of ≈ 13.8 Gyr; moreover, a systematic trend is identified, with larger n leading to higher ages. Furthermore, interacting scenarios consistently predict larger ages compared to their non-interacting counterparts. These results highlight the phenomenological viability and limitations of higher-derivative DE models in describing the cosmic evolution.