On the determination of curvature and dynamical Dark Energy

Abstract

Constraining simultaneously the Dark Energy(DE) equation of state and the curvature of the Universe is difficult due to strong degeneracies. To circumvent this problem when analyzing data it is usual to assume flatness to constrain DE, or conversely, to assume that DE is a cosmological constant to constrain curvature. In this paper, we quantify the impact of such assumptions in view of future large surveys. We simulate future data for type Ia Supernovae (SNIa), Cosmic Microwave Background (CMB) and Baryon Acoustic Oscillations (BAO) for a large range of fiducial cosmologies allowing a small spatial curvature. We take into account a possible time evolution of DE through a parameterized equation of state : $w(a)=w_0+(1-a)w_a$. We then fit the simulated data with a wrong assumption on the curvature or on the DE parameters. For a fiducial $\Lambda$CDM cosmology, if flatness is incorrectly assumed in the fit and if the true curvature is within the ranges $0.01<{\Omega }_k<0.03$ and $-0.07<{\Omega }_k<-0.01$, one will conclude erroneously to the presence of an evolving DE, even with high statistics. On the other hand, models with curvature and dynamical DE can be confused with a flat $\Lambda$CDM model when the fit ignores a possible DE evolution. We find that, in the future, with high statistics, such risks of confusion should be limited, but they are still possible, and biases on the cosmological parameters might be important. We conclude on recalling that, in the future, it will be mandatory to perform some complete multi-probes analyses, leaving the DE parameters as well as the curvature as free parameters.

17 pages, 5 eps figures, final version to be published in JCAP. Several modifications for text and figures but conclusions are unchanged

References in corpus (11)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Dynamics of dark energy
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Improved Cosmological Constraints from New, Old and Combined Supernova Datasets
• Cosmological Constraints from the SDSS Luminous Red Galaxies
• The Dynamics of Quintessence, The Quintessence of Dynamics
• Dynamical Dark Energy or Simply Cosmic Curvature?
• Probing for dynamics of dark energy and curvature of universe with latest cosmological observations
• SPACE: the SPectroscopic All-sky Cosmic Explorer
• A test of the CPL parameterization for rapid dark energy equation of state transitions
• Sensitivity and figures of merit for dark energy supernovae surveys

Cited by in corpus (16)

• The galaxy power spectrum take on spatial curvature and cosmic concordance
• Novel null tests for the spatial curvature and homogeneity of the Universe and their machine learning reconstructions
• Model-independent estimations for the curvature from standard candles and clocks
• Inflation in a closed universe
• Growth factor parametrization in curved space
• Model-independent determination of curvature parameter by using $H(z)$ and $D_A(z)$ data pair from BAO measurement
• Model-independent constraints on cosmic curvature: implication from updated Hubble diagram of high-redshift standard candles
• Model-independent Distance Calibration and Curvature Measurement using Quasars and Cosmic Chronometers
• Exploring the Hubble Tension and Spatial Curvature from the Ages of Old Astrophysical Objects
• Model-independent constraints on cosmic curvature: implication from the future gravitational wave observation DECIGO
• Multiple measurements of gravitational waves acting as standard probes: model-independent constraints on the cosmic curvature with DECIGO
• DECi-hertz Interferometer Gravitational-wave Observatory: Forecast constraints on the cosmic curvature with LSST strong lenses
• Constraints on dark energy from baryon acoustic peak and galaxy cluster gas mass measurements
• The Effects of Spatial Curvature on Cosmic Evolution
• Spatial Curvature and Large Scale Lorentz Violation
• Testing a Sign-Switch Cosmological Model with Curvature through Latest Planck 2018, DESI DR2 and PantheonPlus\&SH0ES Observational Data