What Do We Really Know about Cosmic Acceleration?

Shapiro, Charles A.; Turner, Michael S.

doi:10.1086/506470

Cited by 138 publications

(194 citation statements)

References 37 publications

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“…We could ignore the reconstruction in the region of high redshift (Huterer & Starkman 2003;Shapiro & Turner 2006) or add a physically motivated model for H base in Eq. (10), which would provide us with the value we expect to measure in the upper redshift bound (Tang et al 2008).…”

Section: Minimizing the Bias In The Reconstructionmentioning

confidence: 99%

“…The importance of a model-independent reconstruction of the cosmic expansion rate has already been investigated in the literature (Huterer & Turner 1999, 2000Tegmark 2002;Wang & Tegmark 2005;Mignone & Bartelmann 2008). In this context, PCA has been used to reconstruct the dark-energy equation of state (Huterer & Starkman 2003;Crittenden et al 2009;Simpson & Bridle 2006) and the deceleration parameter (Shapiro & Turner 2006) as a function of redshift. The use of PCA was also proposed in the interpretation of future experiments results by Albrecht et al (2009).…”

Section: Introductionmentioning

confidence: 99%

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Hubbleparameter reconstruction from a principal component analysis: minimizing the bias

Ishida

2011

A&A

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Aims.A model-independent reconstruction of the cosmic expansion rate is essential to a robust analysis of cosmological observations. Our goal is to demonstrate that current data are able to provide reasonable constraints on the behavior of the Hubble parameter with redshift, independently of any cosmological model or underlying gravity theory. Methods. Using type Ia supernova data, we show that it is possible to analytically calculate the Fisher matrix components in a Hubble parameter analysis without assumptions about the energy content of the Universe. We used a principal component analysis to reconstruct the Hubble parameter as a linear combination of the Fisher matrix eigenvectors (principal components). To suppress the bias introduced by the high redshift behavior of the components, we considered the value of the Hubble parameter at high redshift as a free parameter. We first tested our procedure using a mock sample of type Ia supernova observations, we then applied it to the real data compiled by the Sloan Digital Sky Survey (SDSS) group. Results. In the mock sample analysis, we demonstrate that it is possible to drastically suppress the bias introduced by the high redshift behavior of the principal components. Applying our procedure to the real data, we show that it allows us to determine the behavior of the Hubble parameter with reasonable uncertainty, without introducing any ad-hoc parameterizations. Beyond that, our reconstruction agrees with completely independent measurements of the Hubble parameter obtained from red-envelope galaxies.

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Section: Minimizing the Bias In The Reconstructionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hubbleparameter reconstruction from a principal component analysis: minimizing the bias

Ishida

2011

A&A

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“…In the reconstruction of q(z), it was found that the strongest evidence of acceleration happens at redshift z ∼ 0.2 [8,9,10], and the evidence of the current acceleration is not very strong [9] and model dependent [10]. Previous studies on the reconstruction of w(z) also showed that the stringent constraint on w(z), or the sweet spot, happened around redshift z ∼ 0.2 − 0.5 [11,12,13,14,15,16].…”

Section: Introductionmentioning

confidence: 96%

Reconstruction of the deceleration parameter and the equation of state of dark energy

2007

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The new 182 gold supernova Ia data, the baryon acoustic oscillation measurement and the shift parameter determined from the Sloan Digital Sky Survey and the three-year Wilkinson Microwave Anisotropy Probe data are combined to reconstruct the dark energy equation of state parameter w(z) and the deceleration parameter q(z). We find that the strongest evidence of acceleration happens around the redshift z ∼ 0.2 and the stringent constraints on w(z) lie in the redshift range z ∼ 0.2 − 0.5. At the sweet spot, −1.2 < w(z) < −0.6 for the dark energy parametrization w(z) = w0 +waz/(1+z) 2 at the 3σ confidence level. The transition redshift zt when the Universe underwent the transition from deceleration to acceleration is derived to be zt = 0.36−0.08 . The combined data is also applied to find out the geometry of the Universe, and we find that at the 3σ confidence level, |Ω k | < ∼ 0.05 for the simple one parameter dark energy model, and −0.064 < Ω k < 0.028 for the ΛCDM model.

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“…There are very strong model-independent evidences [10] (see also e.g. [11]) for the accelerated expansion.…”

Section: Introductionmentioning

confidence: 98%

Growth index of DGP model and current growth rate data

Hao

2008

Physics Letters B

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Recently, some efforts focus on differentiating dark energy and modified gravity with the growth function δ(z). In the literature, it is useful to parameterize the growth rate f ≡ d ln δ/d ln a = Ω γ m with the growth index γ. In this note, we consider the general DGP model with any Ω k . We confront the growth index of DGP model with currently available growth rate data and find that the DGP model is still consistent with it. This implies that more and better growth rate data are required to distinguish between dark energy and modified gravity.

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What Do We Really Know about Cosmic Acceleration?

Cited by 138 publications

References 37 publications

Hubbleparameter reconstruction from a principal component analysis: minimizing the bias

Hubbleparameter reconstruction from a principal component analysis: minimizing the bias

Reconstruction of the deceleration parameter and the equation of state of dark energy

Growth index of DGP model and current growth rate data

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