Smoothing supernova data to reconstruct the expansion history of the Universe and its age

Shafieloo, Arman; Alam, Ujjaini; Sahni, Varun; Starobinsky, Alexei A.

doi:10.1111/j.1365-2966.2005.09911.x

Cited by 187 publications

(234 citation statements)

References 57 publications

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“…The ansatz (8) is useful not only for reconstructing the DE density but also for determining an important related quantity -the w-probe [22]. As its name suggests, the w-probe provides us with important insights about the equation of state.…”

Section: Resultsmentioning

confidence: 99%

Exploring the properties of dark energy using type-Ia supernovae and other datasets

Alam

Sahni

Starobinsky

2007

J. Cosmol. Astropart. Phys.

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116

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We reconstruct dark energy properties from two complementary supernova datasets -the newly released Gold+HST sample and SNLS. The results obtained are consistent with standard ΛCDM model within 2σ error bars although the Gold+HST data favour evolving dark energy slightly more than SNLS. Using complementary data from baryon acoustic oscillations and the cosmic microwave background to constrain dark energy, we find that our results in this case are strongly dependent on the present value of the matter density Ω0m. Consequently, no firm conclusions regarding constancy or variability of dark energy density can be drawn from these data alone unless the value of Ω0m is known to an accuracy of a few percent. However, possible variability is significantly restricted if this data is used in conjunction with supernova data. INTRODUCTIONThere is a growing consensus in cosmology that the Universe is currently accelerating. Perhaps the simplest explanation of this property is the presence of a positive cosmological constant Λ. Although Λ appears to explain all current observations satisfactorily, to do so its value must necessarily be very small Λ/8πG ≃ 10 −47 GeV 4 . So, it represents a new small constant of nature in addition to those known from elementary particle physics. However, since it is not known at present how to derive it from these other small constants and it is even unclear if it should be exactly constant, other phenomenological explanations for cosmic acceleration have been suggested. Collectively called dark energy (DE) models, they are based either on the introduction of new physical fields (quintessence and phantom models, the Chaplygin gas, etc.), or on geometrical approaches which attempt to generate acceleration by means of a change in the laws of gravity and, therefore, the geometry of space-time [1]. Scalar-tensor gravity, R+ f (R) gravity and higher dimensional 'Braneworld' models are prominent members of this second category.The growing number of DE models has inspired a complementary approach whose aim is to reconstruct properties of DE directly from observations in a quasi-model independent manner, see the recent review [2] and the extensive list of references therein. The aim of this paper is to investigate what new insights can be obtained about DE using the most recent data, and to see whether or not these data strengthen previously obtained results on the closeness of DE to Λ. We study two different supernova samples -the newly released Gold+HST sample [3] and SNLS data [4] to see what constraints follow from them on possible evolution of DE. We also investigate the possibility of extracting information about the nature of DE from datasets other than the supernova data. To this end, we consider what follows from the value of the R parameter characterizing acoustic peaks in the angular power spectrum of the cosmic microwave background (CMB) [5,6] and from the SDSS result on the baryon acoustic oscillation peak (BAO) [7]. DATA AND METHODOLOGYIn this paper, we shall compare the reconstruction re...

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Section: Resultsmentioning

confidence: 99%

Exploring the properties of dark energy using type-Ia supernovae and other datasets

Alam

Sahni

Starobinsky

2007

J. Cosmol. Astropart. Phys.

Self Cite

116

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“…Comparing with those two binning methods listed above, the advantage of this binning method is that it can achieve much smaller χ 2 min 18 . Besides the piecewise constant parametrization, some other local basis representations for w(z) or ρ de (z) are also proposed, such as wavelet [760] and numerical derivatives [566,761]. 18 A simple comparison of these three binning methods can be seen in [759].…”

Section: Binned Parametrizationmentioning

confidence: 99%

Dark Energy

Li¹,

Li²,

Wang³

et al. 2011

Commun. Theor. Phys.

755

560

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“…Not only other parameterizations of dark energy's equation of state have been considered [12], but also parameterizations of the dark energy density alone [9], or of the Hubble parameter [13]. Finally non-parametric tests have been studied [14,15], see e.g. [15] for a general discussion.…”

Section: Introductionmentioning

confidence: 99%

“…Finally non-parametric tests have been studied [14,15], see e.g. [15] for a general discussion. Since CPL is widely implemented in both observational and theoretical studies, it is essential to test its robustness in reconstructing the dynamics of physically motivated dark energy models.…”

Section: Introductionmentioning

confidence: 99%

Test of the Chevallier-Polarski-Linder parametrization for rapid dark energy equation of state transitions

Linden

Virey

2008

Phys. Rev. D

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We test the robustness and flexibility of the Chevallier-Polarski-Linder (CPL) parameterization of the Dark Energy equation of state w(z) = w0 + wa z 1+z in recovering a four-parameter step-like fiducial model. We constrain the parameter space region of the underlying fiducial model where the CPL parameterization offers a reliable reconstruction. It turns out that non negligible biases leak into the results for recent (z < 2.5) rapid transitions, but that CPL yields a good reconstruction in all other cases. The presented analysis is performed with supernova Ia data as forecasted for a space mission like SNAP/JDEM, combined with future expectations for the CMB shift parameter R and the BAO parameter A.

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Smoothing supernova data to reconstruct the expansion history of the Universe and its age

Cited by 187 publications

References 57 publications

Exploring the properties of dark energy using type-Ia supernovae and other datasets

Exploring the properties of dark energy using type-Ia supernovae and other datasets

Dark Energy

Test of the Chevallier-Polarski-Linder parametrization for rapid dark energy equation of state transitions

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