Constraining the dark energy and smoothness parameter with type Ia supernovae and gamma-ray bursts

Busti, V. C.; Santos, R. C.; Lima, J. A. S.

doi:10.1103/physrevd.85.103503

Cited by 21 publications

(31 citation statements)

References 78 publications

(83 reference statements)

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“…It is suggested that a Universe composed only by homogeneously distributed matter is strongly favored by GRB observations. This is greatly different from what was obtained in previous works [32,33].…”

Section: B Long Gamma-ray Burstscontrasting

confidence: 99%

“…Later, Busti et al [32] performed an updated investigation where the statistical analysis was based on the 557 SNe Ia Union2 compilation data [38] and 59 Hymnium GRBs [39], and almost the same conclusion was achieved. More recently, this issue was also studied by using Union2.1 SN Ia [40] plus nine long GRBs in 1.55 ≤ z ≤ 3.57 [41] and the constrained value of the smoothness parameter indicated a clumped Universe [33].…”

Section: Introductionmentioning

confidence: 75%

“…In the past few years, there has been a rich literature concerning the constraints on the smoothness parameter from observations of standard candles [30,[32][33][34]50]. However, we should keep in mind that distances of SNe Ia applied to test the inhomogeneity were estimated from the global fit in the context of a standard homogeneous dark energy model, i.e., the flat ΛCDM or wCDM model.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

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Unbiased constraints on the clumpiness of the Universe from standard candles

Ding

Zhu

2015

Phys. Rev. D

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We perform unbiased tests for the clumpiness of the Universe by confronting the Zel'dovichKantowski-Dyer-Roeder luminosity distance, which describes the effect of local inhomogeneities on the propagation of light with the observational one estimated from measurements of standard candles, i.e., type Ia supernovae (SNe Ia) and gamma-ray bursts (GRBs). Methodologically, we first determine the light-curve fitting parameters which account for distance estimation in SNe Ia observations and the luminosity/energy relations which are responsible for distance estimation of GRBs in the global fit to reconstruct the Hubble diagrams in the context of a clumpy Universe.Subsequently, these Hubble diagrams allow us to achieve unbiased constraints on the matter density parameter Ω m , as well as the clumpiness parameter η which quantifies the fraction of homogeneously distributed matter within a given light cone. At a 1σ confidence level, the constraints are Ω m = 0.34 ± 0.02 and η = 1.00 +0.00 −0.02 from the joint analysis. The results suggest that the Universe full of Friedman-Lemaître-Robertson-Walker fluid is favored by observations of standard candles with very high statistical significance. On the other hand, they may also indicate that the Zel'dovich-Kantowski-Dyer-Roeder approximation is a sufficiently accurate form to describe the effects of local homogeneity on the expanding Universe.

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Section: B Long Gamma-ray Burstscontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 75%

Section: Conclusion and Discussionmentioning

confidence: 99%

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Unbiased constraints on the clumpiness of the Universe from standard candles

Ding

Zhu

2015

Phys. Rev. D

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“…Yu et al [9] got α = 0.81 +0. 19 −0.20 at 1σ CL via the observational H(z) data, and Busti et al [10] got α ≥ 0.25 (2σ) using Union2 SNe Ia data. In this paper we use latest Union2.1 SNe Ia data which contains 580 SNe Ia to constrain α, and we get α = 0.92 +0.08 −0.32 (1σ) and 0.92 +0.08 −0.65 (2σ).…”

Section: Introductionmentioning

confidence: 99%

Constraining smoothness parameter and the DD relation of Dyer-Roeder equation with supernovae

Yang¹,

Yu²,

Zhang

2013

J. Cosmol. Astropart. Phys.

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Abstract. Our real universe is locally inhomogeneous. Dyer and Roeder introduced the smoothness parameter α to describe the influence of local inhomogeneity on angular diameter distance, and they obtained the angular diameter distance-redshift approximate relation (Dyer-Roeder equation) for locally inhomogeneous universe. Furthermore, the DistanceDuality (DD) relation, D L (z)(1 + z) −2 /D A (z) = 1, should be valid for all cosmological models that are described by Riemannian geometry, where D L and D A are, respectively, the luminosity and angular distance distances. Therefore, it is necessary to test whether if the Dyer-Roeder approximate equation can satisfy the Distance-Duality relation. In this paper, we use Union2.1 SNe Ia data to constrain the smoothness parameter α and test whether the Dyer-Roeder equation satisfies the DD relation. By using χ 2 minimization, we get α = 0.92 +0.08 −0.32 at 1σ and 0.92 +0.08 −0.65 at 2σ, and our results show that the Dyer-Roeder equation is in good consistency with the DD relation at 1σ.

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“…GRBs provide a means to test cosmological models once phenomenological relations are used to transform them into stardardizable candles (see [37,38]). For example, they were used to test dark energy models [39,40,41,42] and also possible bias from underdense lines of sight [43]. In this way, in order to have confidence in analyses involving GRBs it is important to verify the existence of cosmic opacity also in high redshifts.…”

Section: Introductionmentioning

confidence: 99%

Probing cosmic opacity at high redshifts with gamma-ray bursts

Holanda

Busti

2014

Phys. Rev. D

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Probing the evolution of the universe at high redshifts with standard candles is a powerful way to discriminate dark energy models, where an open question nowadays is whether this component is constant or evolves with time. One possible source of ambiguity in this kind of analyses comes from cosmic opacity, which can mimick a dark enery behaviour. However, most tests of cosmic opacity have been restricted to the redshift range z < 2. In this work, by using luminosity distances of gamma-ray bursts (GRBs), given the validity of the Amati relation, and the latest H(z) data we determine constraints on the cosmic opacity at high redshifts (z > 2) for a flat ΛCDM model. A possible degenerescence of the results with the adopted cosmological model is also investigated by considering a flat XCDM model. The limits on cosmic opacity in the redshift range 0 < z < 2 are updated with type Ia supernovae (SNe Ia) from the Union2.1 sample, where we added the most distant (z = 1.713) spectroscopically confirmed SNe Ia. From the analyses performed, we find that both SNe Ia and GRBs samples are compatible with a transparent universe at 1σ level and the results are independent of the dark energy equation of state parameter w.

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Constraining the dark energy and smoothness parameter with type Ia supernovae and gamma-ray bursts

Cited by 21 publications

References 78 publications

Unbiased constraints on the clumpiness of the Universe from standard candles

Unbiased constraints on the clumpiness of the Universe from standard candles

Constraining smoothness parameter and the DD relation of Dyer-Roeder equation with supernovae

Probing cosmic opacity at high redshifts with gamma-ray bursts

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