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Diffusive dark fluids with Planck-2018 and DESI BAO DR2 Measurements

Shambel Sahlu, Amare Abebe

Abstract

In this paper, we constrain the diffusive dark fluid cosmological model, which is the interacting dark energy framework, wherein energy is transferred between the two dark components through a diffusion process. We extended the work by S. Sahlu et al. (2026) by employing Cosmic Microwave Background (CMB) data from the Planck 2018 measurements in combination with Baryon Acoustic Oscillation (BAO) data from the Dark Energy Spectroscopic Instrument (DESI) DR2 (2024).From the results, we found that the discrepancies in $H_0$ measurements are $0.0105σ$ and $1.29σ$ between the Planck 2018 value $(H_0 = 67.4\pm0.5\ \mathrm{km,s^{-1},Mpc^{-1}})$ and our diffusive model values, $H_0 = 67.3876^{+1.0765}_{-1.0709}$ and $68.3804^{+0.5639}_{-0.5852}$, respectively. We also the we observe that the effects of the interaction on cosmic evolution and structure formation; we emphasize this by computing the scale-dependent density contrast and the matter power spectrum, compared with the $Λ$CDM model.

Diffusive dark fluids with Planck-2018 and DESI BAO DR2 Measurements

Abstract

In this paper, we constrain the diffusive dark fluid cosmological model, which is the interacting dark energy framework, wherein energy is transferred between the two dark components through a diffusion process. We extended the work by S. Sahlu et al. (2026) by employing Cosmic Microwave Background (CMB) data from the Planck 2018 measurements in combination with Baryon Acoustic Oscillation (BAO) data from the Dark Energy Spectroscopic Instrument (DESI) DR2 (2024).From the results, we found that the discrepancies in measurements are and between the Planck 2018 value and our diffusive model values, and , respectively. We also the we observe that the effects of the interaction on cosmic evolution and structure formation; we emphasize this by computing the scale-dependent density contrast and the matter power spectrum, compared with the CDM model.
Paper Structure (5 sections, 13 equations, 2 figures, 1 table)

This paper contains 5 sections, 13 equations, 2 figures, 1 table.

Table of Contents

  1. Introduction
  2. Basic equations
  3. Linear perturbations in diffusive cosmology
  4. Results and Discussion
  5. Conclusions

Figures (2)

  • Figure 1: The MCMC output for diffusive and $\Lambda$CDM models at 68% and 95% level of confidence space for the posterior parameters for Planck-2018 and Planck-2018+DESI DR2 BAO measurements
  • Figure 2: The scale-dependent density contrast $|\delta|_{m}(z,k)$ for diffusive dark fluid and $\Lambda$CDM models.