Constraining the dark energy and smoothness parameter with type Ia Supernovae and Gamma-Ray Bursts

Abstract

The existence of inhomogeneities in the observed Universe modifies the distance-redshift relations thereby affecting the results of cosmological tests in comparison to the ones derived assuming spatially uniform models. By modeling the inhomogeneities through a Zeldovich-Kantowski-Dyer-Roeder (ZKDR) approach which is phenomenologically characterized by a smoothness parameter $\alpha$, we rediscuss the constraints on the cosmic parameters based on Supernovae type Ia and Gamma-Ray Bursts (GRBs) data. The present analysis is restricted to a flat $\Lambda$CDM model with the reasonable assumption that $\Lambda$ does not clump. A ${\chi }^2$-analysis using 557 SNe Ia data from the Union2 Compilation Data (Amanullah {\it et al.} 2010) constrains the pair of parameters (${\Omega }_m,\alpha$) to ${\Omega }_m=0.27_{-0.03}^{+0.08}$($2\sigma$) and $\alpha \ge 0.25$. A similar analysis based only on 59 Hymnium GRBs (Wei 2010) constrains the matter density parameter to be ${\Omega }_m=0.35_{-0.24}^{+0.62}$ ($2\sigma$) while all values for the smoothness parameter are allowed. By performing a joint analysis, it is found that ${\Omega }_m=0.27_{-0.03}^{+0.06}$ and $\alpha \ge 0.52$. As a general result, although considering that current GRB data alone cannot constrain the smoothness $\alpha$ parameter our analysis provides an interesting cosmological probe for dark energy even in the presence of inhomogeneities.

7 pages, 4 figures, corrected version accepted for publication in Physical Review D

References in corpus (17)

• The Supernova -- Gamma-Ray Burst Connection
• New Hubble Space Telescope Discoveries of Type Ia Supernovae at z > 1: Narrowing Constraints on the Early Behavior of Dark Energy
• Spectra and Light Curves of Six Type Ia Supernovae at 0.511 < z < 1.12 and the Union2 Compilation
• The Hubble Diagram to Redshift >6 from 69 Gamma-Ray Bursts
• A Cosmology-Independent Calibration of Gamma-Ray Burst Luminosity Relations and the Hubble Diagram
• Time drift of cosmological redshifts as a test of the Copernican principle
• Testing the Distance-Duality Relation with Galaxy Clusters and Type Ia Supernovae
• Model-Independent Distance Measurements from Gamma-Ray Bursts and Constraints on Dark Energy
• Gamma-Ray Bursts in $1.8<z<5.6$ Suggest that the Time Variation of the Dark Energy is Small
• Oscillations in the dark energy EoS: new MCMC lessons
• A Significant Problem With Using the Amati Relation for Cosmological Purposes
• Constraints on $w_0$ and $w_a$ of Dark Energy from High Redshift Gamma Ray Bursts
• Clustering, Angular Size and Dark Energy
• Gamma-ray burst contributions to constraining the evolution of dark energy
• Constraining the dark energy and smoothness-parameter with supernovae
• Statistics of gravitational lenses in the clumpy Universe
• An overview of the current understanding of Gamma-ray Bursts in the Fermi era

Cited by in corpus (15)

• Observational constraints on non-flat dynamical dark energy cosmological models
• Probing cosmic opacity at high redshifts with gamma-ray bursts
• Constraints on dark energy from the Lyα forest baryon acoustic oscillations measurement of the redshift 2.3 Hubble parameter
• On tidal forces in f(R) theories of gravity
• Constraining smoothness parameter and the DD relation of Dyer-Roeder equation with supernovae
• Observational constraints on dark energy cosmological model parameters
• Mapping the inhomogeneous Universe with Standard Sirens: Degeneracy between inhomogeneity and modified gravity theories
• Supernovae as probes of cosmic parameters: estimating the bias from under-dense lines of sight
• Observational constraints from SNe Ia and Gamma-Ray Bursts on a clumpy universe
• Understanding the Dyer-Roeder approximation as a consequence of local cancellations of projected shear and expansion rate fluctuations
• Constraining Temporal Oscillations of Cosmological Parameters Using Type Ia Supernovae
• Unbiased constraints on the clumpiness of universe from standard candles
• Influence of Small-Scale Inhomogeneities on the Cosmological Consistency Tests
• Studying light propagation in a locally homogeneous universe through an extended Dyer-Roeder approach
• Observations of General Relativity at strong and weak limits