G

Gerke, Wolfgang

doi:10.1007/978-3-322-82631-2_7

Cited by 28 publications

(45 citation statements)

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“…It is also important to check whether the results of our reconstruction can be replicated using other Ansatz such as fits to the luminosity distance or the equation of state. Many different fits have been suggested in the literature (see for example Huterer & Turner 1999;Saini et al 2000;Weller & Albrecht 2002;Gerke & Efstathiou 2002). Here we choose the fit suggested in Linder (2003) in which the equation of state of DE is expanded as…”

Section: Using Other Ansatzmentioning

confidence: 99%

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Is there supernova evidence for dark energy metamorphosis?

Alam

Sahni

Saini

et al. 2004

Monthly Notices of the Royal Astronomical Society

497

433

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We reconstruct the equation of state w(z) of dark energy (DE) using a recently released data set containing 172 Type Ia supernovae (SNe) without assuming the prior w(z) ≥−1 (in contrast to previous studies). We find that DE evolves rapidly and metamorphoses from dust‐like behaviour at high z (w≃ 0 at z∼ 1) to a strongly negative equation of state at present (w≲−1 at z≃ 0). DE metamorphosis appears to be a robust phenomenon which manifests for a large variety of SNe data samples provided one does not invoke the weak energy prior ρ+p≥ 0. Invoking this prior considerably weakens the rate of growth of w(z). These results demonstrate that DE with an evolving equation of state provides a compelling alternative to a cosmological constant if data are analysed in a prior‐free manner and the weak energy condition is not imposed by hand.

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Section: Using Other Ansatzmentioning

confidence: 99%

“…3 Alternatively, one could apply an Ansatz to w(z) itself (Chiba & Nakamura 2000;Weller & Albrecht 2002;Gerke & Efstathiou 2002;Maor et al 2002;Linder 2003). See for a summary of different approaches to cosmological reconstruction.…”

mentioning

confidence: 99%

Is there supernova evidence for dark energy metamorphosis?

Alam

Sahni

Saini

et al. 2004

Monthly Notices of the Royal Astronomical Society

497

433

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“…[There is extensive literature on determining dark energy parameters from the current and proposed future supernova observations (e.g. see Maor et al 2002;Weller & Albrecht 2002;Gerke & Efstathiou 2002 and references therein)]. As before, we assume a flat Universe with a fixed value of m in the range (0.21-0.41) and M is fixed to the corresponding best-fitting value.…”

Section: O N S T R a I N T S O N E Vo Lv I N G Da R K E N E R G Ymentioning

confidence: 99%

A theoretician's analysis of the supernova data and the limitations in determining the nature of dark energy

Padmanabhan

Choudhury

2003

Monthly Notices RAS

275

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Current cosmological observations show a strong signature of the existence of a dark energy component with negative pressure. The most obvious candidate for this dark energy is the cosmological constant (with the equation of state wX=p/ρ=−1), which, however, raises several theoretical difficulties. This has led to models for a dark energy component that evolves with time. We discuss certain questions related to the determination of the nature of the dark energy component from observations of high‐redshift supernovae. The main results of our analysis are as follows. (i) Even if the precise value of wX is known from observations, it is not possible to determine the nature of the unknown dark energy source using only kinematical and geometrical measurements. We have given explicit examples to show that different types of sources can give rise to a given wX. (ii) Although the full data set of supernova observations (which are currently available) strongly rule out models without dark energy, the high‐Ψ(z > 0.25) and low‐ (z < 0.25) redshift data sets, individually, admit decelerating models with zero dark energy. Any possible evolution in the absolute magnitude of the supernovae, if detected, might allow the decelerating models to be consistent with the data. (iii) We have introduced two parameters, which can be obtained entirely from theory, to study the sensitivity of the luminosity distance on wX. Using these two parameters, we have argued that although one can determine the present value of wX accurately from the data, one cannot constrain the evolution of wX.

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“…Much attention in recent years has focused on determining the properties of dark energy in a model-independent manner. This can be done using either parametric (Starobinsky 1998;Huterer & Turner 1999;Chiba & Nakamura 2000;Saini et al 2000;Chevallier & Polarski 2001;Gerke & Efstathiou 2002;Maor et al 2002;Weller & Albresht 2002;Alam et al 2003;Corasaniti & Copeland 2003;Linder 2003a;Nesseris & Perivolaroupolos 2004;Saini, Weller & Bridle 2004;Wang & Mukherjee 2004;Gong 2005;Linder & Huterer 2005 Gong & Wang 2007; Alam, Sahni & Starobinsky 2007) or non-parametric methods (Wang & Lovelace 2001;Daly & Djorgovsky 2003;Huterer & Starkman 2003;Saini 2003;Wang & Tegmark 2004Huterer & Cooray 2005;Bonvin, Durrer & Kunz 2006;Fay & Tavakol 2006;Shafieloo et al 2006). A comprehensive recent review has been given by .…”

Section: Introductionmentioning

confidence: 99%

Model-independent reconstruction of the expansion history of the Universe and the properties of dark energy

Shafieloo¹

2007

Monthly Notices of the Royal Astronomical Society

107

154

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We have improved upon the method of smoothing supernovae data to reconstruct the expansion history of the Universe, h(z), using two latest data sets, Gold and Supernovae Legacy Survey (SNLS). The reconstruction process does not employ any parametrization and is independent of any dark energy model. The reconstructed h(z) is used to derive the distance factor A up to redshift 0.35 and the results are compared with the given value of A from detection of the baryon acoustic oscillation peak. We find very good agreement between supernovae observations and the results from the baryon acoustic oscillation peak for Ω0m≈ 0.276 ± 0.023. The estimated values of Ω0m are completely model‐independent and are only based on observational data. The derived values of Ω0m are then used to reconstruct the equation of state of dark energy, w(z). Using our smoothing method, we can demonstrate that while SNLS data are in very good agreement with Λ cold dark matter (ΛCDM), the Gold sample slightly prefers evolving dark energy. We also show that proper estimation of the equation of state of dark energy at the high redshifts would be impossible at the current status of observations.

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G

Cited by 28 publications

References 0 publications

Is there supernova evidence for dark energy metamorphosis?

Is there supernova evidence for dark energy metamorphosis?

A theoretician's analysis of the supernova data and the limitations in determining the nature of dark energy

Model-independent reconstruction of the expansion history of the Universe and the properties of dark energy

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