On the Degeneracy Inherent in Observational Determination of the Dark Energy Equation of State

Abstract

Using a specific model for the expansion rate of the Universe as a function of scale factor, it is demonstrated that the equation of state of the dark energy cannot be determined uniquely from observations at redshifts $z\lesssim \mathrm{afew}$ unless the fraction of the mass density of the Universe in nonrelativistic particles, ${\Omega }_M$, somehow can be found independently. A phenomenological model is employed to discuss the utility of additional constraints from the formation of large scale structure and the positions of CMB peaks in breaking the degeneracy among models for the dark energy.

arXiv comment12 pages, 3 figures. Several references added

References in corpus (30)

• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• Cosmological Imprint of an Energy Component with General Equation of State
• A Flat Universe from High-Resolution Maps of the Cosmic Microwave Background Radiation
• Cosmology with a Primordial Scaling Field
• Supernova Limits on the Cosmic Equation of State
• CDM Models with a Smooth Component
• Constraining dark energy with SNe Ia and large-scale structure
• Cosmology from Maxima-1, Boomerang and COBE/DMR CMB Observations
• Probing the dark energy: methods and strategies
• Prospects for probing the dark energy via supernova distance measurements
• Cosmic Concordance and Quintessence
• Reconstructing the Cosmic Equation of State from Supernova distances
• First Estimations of Cosmological Parameters From BOOMERANG
• Multiple Peaks in the Angular Power Spectrum of the Cosmic Microwave Background: Significance and Consequences for Cosmology
• Cosmological Parameter Extraction from the First Season of Observations with DASI
• Constraining the equation of state of the Universe from Distant Type Ia Supernovae and Cosmic Microwave Background Anisotropies
• Cosmological implications of the MAXIMA-I high resolution Cosmic Microwave Background anisotropy measurement
• Limitations in using luminosity distance to determine the equation of state of the universe
• Current constraints on the dark energy equation of state
• Prospects for Determining the Equation of State of the Dark Energy: What can be Learned from Multiple Observables?
• Measuring Time-Dependence of Dark Energy Density from Type Ia Supernova Data
• Supernovae Ia Constraints on a Time-Variable Cosmological "Constant"
• Feasibility of Reconstructing the Quintessential Potential Using SNIa Data
• Quintessence Model With Double Exponential Potential
• Measuring the Cosmic Equation of State with Counts of Galaxies II: Error Budget for the DEEP2 Redshift Survey
• Measuring the Cosmic Equation of State with Counts of Galaxies
• Cosmological properties of a class of $\Lambda$ decaying cosmologies
• Cosmological Parameter Determination from Counts of Galaxies
• Determining the Equation of State of the Expanding Universe Using a New Independent Variable

Cited by in corpus (35)

• The Cosmological Constant and Dark Energy
• Constraints on the generalized Chaplygin gas from supernovae observations
• Model-Independent Constraints on Dark Energy Density from Flux-averaging Analysis of Type Ia Supernova Data
• DESI 2024: Reconstructing Dark Energy using Crossing Statistics with DESI DR1 BAO data
• A litmus test for Lambda
• The dark degeneracy: On the number and nature of dark components
• The dark degeneracy and interacting cosmic components
• Revisiting Generalized Chaplygin Gas as a Unified Dark Matter and Dark Energy Model
• Looking for interactions in the cosmological dark sector
• Modified Chaplygin Gas as a Unified Dark Matter and Dark Energy Model and Cosmic Constraints
• Dark degeneracy I: Dynamical or interacting dark energy?
• Unified dark energy and dark matter from a scalar field different from quintessence
• Model-independent dark energy differentiation with the ISW effect
• Observational tests of non-adiabatic Chaplygin gas
• Unified Dark Fluid with Constant Adiabatic Sound Speed and Cosmic Constraints
• Constraining the dark fluid
• Determining the equation of state of dark energy from angular size of compact radio sources and X-ray gas mass fraction of galaxy clusters
• Extending the generalized Chaplygin gas model by using geometrothermodynamics
• On dark degeneracy and interacting models
• Dark matter from dark energy-baryonic matter couplings
• Constraints on a decomposed dark fluid with constant adiabatic sound speed by jointing the geometry test and growth rate after Planck data
• J-PAS: forecasts on interacting vacuum energy models
• Unified Dark Fluid with Constant Adiabatic Sound Speed: Including Entropic Perturbations
• Inverse Power Law Quintessence with Non-Tracking Initial Conditions
• Cosmological dark fluid from five-dimensional vacuum
• Degeneracy between CCDM and $\Lambda$CDM cosmologies
• Decaying dark matter mimicking time-varying dark energy
• One-parameter dynamical dark-energy from the generalized Chaplygin gas
• Spherical Collapse of a Unified Dark Fluid with Constant Adiabatic Sound Speed
• Why we need to see the dark matter to understand the dark energy
• Unified dark fluid with fast transition: including entropic perturbations
• Impact of the matter density uncertainty on the dark energy reconstruction
• Unified dark fluid with null sound speed as an alternative to phantom dark energy
• The cosmological dark sector as a scalar $\sigma$-meson field
• Phenomenological aspects of dark energy dominated cosmologies