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Current observations favour phantom-enhanced nature of dark energy

Md. Wali Hossain

TL;DR

The paper investigates whether present cosmological data prefer phantom-enhanced dynamical dark energy over the standard $\Lambda$CDM paradigm. It introduces two new two-parameter EoS forms, PL and MPL, that permit more flexible $w(a)$ evolution and stronger phantom behavior than the CPL form. Using MCMC fits to datasets including PantheonPlus, Union3, and DESY5 (along with CMB and RSD data), the authors compare $\Lambda$CDM, CPL, BA, EXP, PL, and MPL via information criteria and tension analyses. They find that PL is the most favored among the models tested and that increased phantom evolution is associated with larger tension with $\Lambda$CDM, suggesting current data prefer extended phantom dynamics and guiding future parametrization development.

Abstract

Our study shows that the more a dark energy model allows the equation of state to become phantom-like toward the past, the better it fits current observations which also may lead to stronger statistical tension with $Λ$CDM. In particular, models with greater flexibility in their redshift evolution, such as power-law type forms, are mildly preferred over more restrictive parametrizations with similar parameter dimensionality. For the dataset including DESY5, the deviation from $Λ$CDM reaches a significance of $6.26σ$. These results indicate that present data are sensitive to enhanced phantom behaviour and provide clear guidance for constructing phenomenologically viable dark energy parametrizations.

Current observations favour phantom-enhanced nature of dark energy

TL;DR

The paper investigates whether present cosmological data prefer phantom-enhanced dynamical dark energy over the standard CDM paradigm. It introduces two new two-parameter EoS forms, PL and MPL, that permit more flexible evolution and stronger phantom behavior than the CPL form. Using MCMC fits to datasets including PantheonPlus, Union3, and DESY5 (along with CMB and RSD data), the authors compare CDM, CPL, BA, EXP, PL, and MPL via information criteria and tension analyses. They find that PL is the most favored among the models tested and that increased phantom evolution is associated with larger tension with CDM, suggesting current data prefer extended phantom dynamics and guiding future parametrization development.

Abstract

Our study shows that the more a dark energy model allows the equation of state to become phantom-like toward the past, the better it fits current observations which also may lead to stronger statistical tension with CDM. In particular, models with greater flexibility in their redshift evolution, such as power-law type forms, are mildly preferred over more restrictive parametrizations with similar parameter dimensionality. For the dataset including DESY5, the deviation from CDM reaches a significance of . These results indicate that present data are sensitive to enhanced phantom behaviour and provide clear guidance for constructing phenomenologically viable dark energy parametrizations.

Paper Structure

This paper contains 7 sections, 7 equations, 4 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Models
  3. Data analysis
  4. Observational Data
  5. Model selection and statistical tension
  6. Results
  7. Conclusions

Figures (4)

  • Figure 1: Left: Dark energy density $\rho(z)$ is plotted against redshift $z$ for PL, MPL and CPL. Right: The corresponding EoS ($w(z)$) is plotted against $z$. Both panels use identical values of $w_0$ and $w_a$ for all models.
  • Figure 2: $1\sigma$ and $2\sigma$ confidence contours for the parameters of PL (left) and MPL (right) models.
  • Figure 3: $1\sigma$ and $2\sigma$ confidence contours for the parameters $w_0$ and $w_a$ in the PL, MPL, CPL, BA and EXP models.
  • Figure 4: Reconstructed EoS in PL, MPL, CPL, BA and EXP models with the median value (lines) and 1$\sigma$ errors (shaded region).