Measuring the Equation-of-state of the Universe: Pitfalls and Prospects

Abstract

We explore various pitfalls and challenges in determining the equation-of-state (w) of dark energy component that dominates the universe and causes the current accelerated expansion. We demonstrated in an earlier paper the existence of a degeneracy that makes it impossible to resolve well the value of w or its time-derivative with supernovae data. Here we consider standard practices, such as assuming priors that w is constant or greater than -1, and show that they also can lead to gross errors in estimating the true equation-of-state. We further consider combining measurements of the cosmic microwave background anisotropy and the Alcock-Paczynski test with supernovae data and find that the improvement in resolving the time-derivative of w is marginal, although the combination can constrain its present value perhaps to 20 percent uncertainty.

27 pages, 10 figures

References in corpus (6)

• Cosmology and the Fate of Dilatation Symmetry
• Future Supernovae observations as a probe of dark energy
• Constraining the quintessence equation of state with SnIa data and CMB peaks
• Unbiased Estimate of Dark Energy Density from Type Ia Supernova Data
• Dark Energy and the Observable Universe
• Future supernova probes of quintessence

Cited by in corpus (149)

• Dynamics of dark energy
• The Cosmological Constant and Dark Energy
• Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red Galaxies
• Constraints on the redshift dependence of the dark energy potential
• Can the dark energy equation-of-state parameter w be less than -1?
• Quantum deSitter cosmology and phantom matter
• Exploring the Expanding Universe and Dark Energy using the Statefinder Diagnostic
• Dark Energy
• Probing Dark Energy with Baryonic Acoustic Oscillations from Future Large Galaxy Redshift Surveys
• Braneworld models of dark energy
• Reconstructing Dark Energy
• Two new diagnostics of dark energy
• Dark Matter and Dark Energy
• Interacting quintessence solution to the coincidence problem
• Cosmological Dynamics of Phantom Field
• Is there Supernova Evidence for Dark Energy Metamorphosis ?
• The State of the Dark Energy Equation of State
• Approaches to Understanding Cosmic Acceleration
• Parameterization of Dark-Energy Properties: a Principal-Component Approach
• Super-acceleration as Signature of Dark Sector Interaction
• A theoretician's analysis of the supernova data and the limitations in determining the nature of dark energy
• Cosmological parameters from supernova observations: A critical comparison of three data sets
• Phantom Field and the Fate of Universe
• New dark energy constraints from supernovae, microwave background and galaxy clustering
• A parametric model for dark energy
• A comparison of cosmological models using recent supernova data
• Large Scale Cosmic Microwave Background Anisotropies and Dark Energy
• deSitter brane universeinduced by phantom and quantum effects
• The foundations of observing dark energy dynamics with the Wilkinson Microwave Anisotropy Probe
• Effective equation of state and energy conditions in phantom/tachyon inflationary cosmology perturbed by quantum effects
• Scalar-Tensor Models of Normal and Phantom Dark Energy
• Eppur è piatto? The cosmic chronometer take on spatial curvature and cosmic concordance
• Latest Supernova data in the framework of Generalized Chaplygin Gas model
• Smoothing Supernova Data to Reconstruct the Expansion History of the Universe and its Age
• The essence of quintessence and the cost of compression
• Model-Independent Constraints on Dark Energy Density from Flux-averaging Analysis of Type Ia Supernova Data
• Dynamical dark energy: Current constraints and forecasts
• A model independent approach to the dark energy equation of state
• Future supernovae data and quintessence models
• Dark energy cosmology with generalized linear equation of state
• Dark Energy and Matter Evolution from Lensing Tomography
• Cosmological structure formation in a homogeneous dark energy background
• Parametrizations of the Dark Energy Density and Scalar Potentials
• Phantom Cosmologies
• Dipole of the luminosity distance: a direct measure of H(z)
• Phantom-like GCG and the constraints of its parameters via cosmological dynamics
• Gradient instability for w < -1
• Model Independent Reconstruction of the Expansion History of the Universe and the Properties of Dark Energy
• Phantom Cosmic Dynamics: Tracking Attractor and Cosmic Doomsday
• Phantom with Born-Infield type Lagrangian
• Can we be tricked into thinking that w is less than -1?
• Supergravity, Dark Energy and the Fate of the Universe
• Exorcising w < -1
• Constraining the Evolution of Dark Energy with a Combination of Galaxy Cluster Observables
• Phantom Field with O(N) Symmetry in Exponential Potential
• Dynamical behavior of generic quintessence potentials: constraints on key dark energy observables
• Cosmological Constraints from Compact Radio Source Angular Size versus Redshift Data
• Born-Infeld-type phantom on the brane world
• Revealing the Nature of Dark Energy Using Bayesian Evidence
• Tracking Dark Energy with the ISW effect: short and long-term predictions
• Falsifying Paradigms for Cosmic Acceleration
• Constraints on reconstructed dark energy model from SN Ia and BAO/CMB observations
• Quintessence reconstructed: new constraints and tracker viability
• On the determination of the deceleration parameter from Supernovae data
• Radio Galaxy Redshift-Angular Size Data Constraints on Dark Energy
• Mapping the Chevallier-Polarski-Linder parametrization onto Physical Dark Energy Models
• Dark Matter and Dark Energy: Summary and Future Directions
• Dark Energy Evolution and the Curvature of the Universe from Recent Observations
• Late Universe expansion dominated by domain walls and dissipative dark matter
• Testing the Cosmological Constant as a Candidate for Dark Energy
• Voids of dark energy
• Transient Accelerated Expansion and Double Quintessence
• On the equation of state of Dark Energy
• Cosmological constraints combining H(z), CMB shift and SNIa observational data
• Constraints on a variable dark energy model with recent observations
• A test of the CPL parameterization for rapid dark energy equation of state transitions
• Brane-bulk energy exchange : a model with the present universe as a global attractor
• Dark energy: investigation and modeling
• Testing a new analytic model for gravitational lensing probabilities
• On the determination of curvature and dynamical Dark Energy
• Dark Energy and the Fate of the Universe
• Probing decisive answers to dark energy questions from cosmic complementarity and lensing tomography
• On the density of Cold Dark Matter
• Stable Models of superacceleration
• Modified Holographic Dark Energy
• Model-independent dark energy test with sigma_8 using results from the Wilkinson Microwave Anisotropy Probe
• The Redshift Sensitivities of Dark Energy Surveys
• Separating out the Alcock-Paczynski Effect on 21cm Fluctuations
• Determining the equation of state of dark energy from angular size of compact radio sources and X-ray gas mass fraction of galaxy clusters
• Legacy data and cosmological constraints from the angular-size/redshift relation for ultra-compact radio sources
• Distinguishing among Scalar Field Models of Dark Energy
• Cosmic Mimicry: Is LCDM a Braneworld in Disguise ?
• Growth index with the exact analytic solution of sub-horizon scale linear perturbation for dark energy models with constant equation of state
• FLRW cosmology with EDSFD parametrization
• Dark energy reconstruction based on the PADE approximation; an expansion around the $\Lambda$CDM
• Extending the Coyote emulator to dark energy models with standard $w_0$-$w_a$ parametrization of the equation of state
• Galaxy Clustering and Dark Energy
• Tracking Quintessence Would Require Two Cosmic Coincidences
• The Accelerated Acceleration of the Universe
• Hairy Kiselev Black Hole Solutions
• The Lame${}^{\prime }$ Equation for Distance-Redshift in Partially Filled Beam Friedmann-Lema\^ıtre-Robertson-Walker Cosmology
• Model-independent determination of the cosmic expansion rate. I. Application to type-Ia supernovae
• Phantom cosmology as a simple model with dynamical complexity
• Probing the Evolution of the Dark Energy Density with Future Supernova Surveys
• Illuminating Dark Energy with Cosmic Shear
• Response of distance measures to the equation of state
• Oxidised cosmic acceleration
• How Sensitive Are Weak Lensing Statistics to Dark Energy Content?
• Exploring hints for dark energy density evolution in light of recent data
• Constraining Dark Energy and Cosmological Transition Redshift with Type Ia Supernovae
• Evolving dark energy equation of state and CMB/LSS cross-correlation
• Prospects for Dark Energy Evolution: a Frequentist Multi-Probe Approach
• Reconstructing the properties of dark energy from recent observations
• Probing Dark Energy with Supernovae : Bias from the time evolution of the equation of state
• Probing Dark Energy with Supernovae : a concordant or a convergent model?
• Optimized supernova constraints on dark energy evolution
• A new parametrization for dark energy density and future deceleration
• Testing for a Super-Acceleration Phase of the Universe
• Properties of the exact analytic solution of the growth factor and its applications
• Stringy Instability of Topologically Non-Trivial Ads Black Holes and of desitter S-Brane Spacetimes
• An optimal basis system for cosmology: data analysis and new parameterisation
• Galileons, phantom fields, and the fate of the Universe
• Constraining dark energy using the cross correlations of weak lensing with post-reionization probes of neutral hydrogen
• Prospects in Constraining the Dark Energy Potential
• Gravitational Quasinormal Modes of Regular Phantom Black Hole
• Probing the cosmic acceleration history and the properties of dark energy from the ESSENCE supernova data with a model independent method
• Observational constraints on the time-dependence of dark energy
• Evolution of density perturbations in double exponential quintessence models
• Direct reconstruction of dynamical dark energy from observational Hubble parameter data
• An Alternative Approach to Holographic Dark Energy
• Effect of low anisotropy on cosmological models by using supernova data
• Constraining Temporal Oscillations of Cosmological Parameters Using Type Ia Supernovae
• Fitting inverse power-law quintessence models using the SNAP satellite
• Falsifying Cosmological Constant
• Forecasting Super-Sample Covariance in Future Weak Lensing Surveys with SuperSCRAM
• Using bright ellipticals as dark energy cosmic clocks
• "Expansion" around the vacuum: how far can we go from Lambda?
• Complementarity of Future Dark Energy Probes
• Expressing the equation of state parameter in terms of the three dimensional cosmic shear
• Is Chevallier-Polarski-Linder dark energy a mirage?
• A measure of cosmological distance using the \civ\ Baldwin effect in quasars
• The reconstruction of dark energy with Ridge Regression Approach
• Tracker coupled quintessence
• A cosmological distance measure using radio-loud quasars
• Phenomenological aspects of dark energy dominated cosmologies
• Expanding Universe: Thermodynamical Aspects From Different Models
• Probing Time-Varying Dark Energy with DESI: The Crucial Role of Precision Matter Density (Ω_{m0}) Measurements
• Determining the expansion history of the universe with the three dimensional cosmic shear
• Biased Cosmology: Pivots, Parameters, and Figures of Merit