Statefinder revisited

Ishida, Emille E. O.

doi:10.1590/s0103-97332005000700045

Cited by 10 publications

(11 citation statements)

References 4 publications

(7 reference statements)

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“…So here we quote the observed uncertainties on diagnostic parameters obtained in previous works. Uncertainties on S (1) 3 and S (1) 4 from current observations or estimated from simulations can be found in [34,[69][70][71][72][73][74]. It was found that they are rather difficult to measure-for most of the fit results, the uncertainties on S…”

Section: Probing Deviations From λCdm In the Iλcdm Modelsmentioning

confidence: 99%

A closer look at interacting dark energy with statefinder hierarchy and growth rate of structure

Cui

Yin

Wang

et al. 2015

J. Cosmol. Astropart. Phys.

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We investigate the interacting dark energy models by using the diagnostics of statefinder hierarchy and growth rate of structure. We wish to explore the deviations from ΛCDM and to differentiate possible degeneracies in the interacting dark energy models with the geometrical and structure growth diagnostics. We consider two interacting forms for the models, i.e., Q 1 = βHρ c and Q 2 = βHρ de , with β being the dimensionless coupling parameter. Our focus is the IΛCDM model that is a one-parameter extension to ΛCDM by considering a direct coupling between the vacuum energy (Λ) and cold dark matter (CDM), with the only additional parameter β. But we begin with a more general case by considering the IwCDM model in which dark energy has a constant w (equation-of-state parameter). For calculating the growth rate of structure, we employ the "parametrized post-Friedmann" theoretical framework for interacting dark energy to numerically obtain the (z) values for the models. We show that in both geometrical and structural diagnostics the impact of w is much stronger than that of β in the IwCDM model. We thus wish to have a closer look at the IΛCDM model by combining the geometrical and structural diagnostics. We find that the evolutionary trajectories in the S (1) 3 -plane exhibit distinctive features and the departures from ΛCDM could be well evaluated, theoretically, indicating that the composite null diagnostic {S (1) 3 , } is a promising tool for investigating the interacting dark energy models. We also compare our results with the observed uncertainties on diagnostic parameters. We find that current observations still do not have sufficient precisions to completely distinguish IΛCDM models from the ΛCDM model. Anyway, our work points out what precisions of measurements should be achieved to distinguish the IΛCDM models from the ΛCDM model.

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Section: Probing Deviations From λCdm In the Iλcdm Modelsmentioning

confidence: 99%

A closer look at interacting dark energy with statefinder hierarchy and growth rate of structure

Cui

Yin

Wang

et al. 2015

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

show abstract

“…Since these publications, several efforts have been made to explain these observations (Cunha et al 2009;Frieman et al 2008;Linder 2008;Linder & Huterer 2005;Samsing & Linder 2010;Freaza et al 2002;Ishida 2005;Ishida et al 2008, and references therein). In a standard analysis, dark-energy models are characterized by a small set of parameters.…”

Section: Introductionmentioning

confidence: 99%

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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“…So here we quote the observed uncertainties on diagnostic parameters obtained in previous works. Uncertainties on S 4 from current observations or estimated from simulations can be found in [34,[69][70][71][72][73][74]. It was found that they are rather difficult to measure-for most of the fit results, the uncertainties on S 4 are larger than the maximum differences [5% (4%) and 15% (3%)] between the ΛCDM model and the IΛCDM1 (IΛCDM2) model, indicating that neither the IΛCDM1 model nor the IΛCDM2 model can be well distinguished from the ΛCDM model.…”

Section: Probing Deviations From λCdm In the Iλcdm Modelsmentioning

confidence: 99%

A closer look at interacting dark energy with statefinder hierarchy and growth rate of structure

Cui

Yin

Wang

et al. 2015

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

Abstract. We investigate the interacting dark energy models by using the diagnostics of statefinder hierarchy and growth rate of structure. We wish to explore the deviations from ΛCDM and to differentiate possible degeneracies in the interacting dark energy models with the geometrical and structure growth diagnostics. We consider two interacting forms for the models, i.e., Q 1 = βHρ c and Q 2 = βHρ de , with β being the dimensionless coupling parameter. Our focus is the IΛCDM model that is a one-parameter extension to ΛCDM by considering a direct coupling between the vacuum energy (Λ) and cold dark matter (CDM), with the only additional parameter β. But we begin with a more general case by considering the IwCDM model in which dark energy has a constant w (equation-of-state parameter). For calculating the growth rate of structure, we employ the "parametrized post-Friedmann" theoretical framework for interacting dark energy to numerically obtain the (z) values for the models. We show that in both geometrical and structural diagnostics the impact of w is much stronger than that of β in the IwCDM model. We thus wish to have a closer look at the IΛCDM model by combining the geometrical and structural diagnostics. We find that the evolutionary trajectories in the S (1) 3 -plane exhibit distinctive features and the departures from ΛCDM could be well evaluated, theoretically, indicating that the composite null diagnostic {S (1) 3 , } is a promising tool for investigating the interacting dark energy models. We also compare our results with the observed uncertainties on diagnostic parameters. We find that current observations still do not have sufficient precisions to completely distinguish IΛCDM models from the ΛCDM model. Anyway, our work points out what precisions of measurements should be achieved to distinguish the IΛCDM models from the ΛCDM model.

show abstract

Statefinder revisited

Cited by 10 publications

References 4 publications

A closer look at interacting dark energy with statefinder hierarchy and growth rate of structure

A closer look at interacting dark energy with statefinder hierarchy and growth rate of structure

Hubbleparameter reconstruction from a principal component analysis: minimizing the bias

A closer look at interacting dark energy with statefinder hierarchy and growth rate of structure

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