Small‐Scale Cosmological Perturbations: An Analytic Approach

Hu, Wayne; Sugiyama, Naoshi

doi:10.1086/177989

Cited by 909 publications

(953 citation statements)

References 31 publications

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“…For calculating this quantity, we use Ω b h 2 = 0.024 and Ω 0m h 2 = 0.14 ± 0.02. To calculate z ls we use a fitting function given in [16]:…”

Section: Methodsmentioning

confidence: 99%

“…For calculating this quantity, we use Ω b h 2 = 0.024 and Ω 0m h 2 = 0.14 ± 0.02. To calculate z ls we use a fitting function given in [16]:where the quantities g 1 , g 2 are defined as2. The Baryon Acoustic Oscillation Peak : A remarkable confirmation of the standard big bang cosmology has been the recent detection of a peak in the correlation function of luminous red galaxies in the Sloan Digital Sky Survey [7].…”

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confidence: 99%

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

Alam

Sahni

Starobinsky

2007

J. Cosmol. Astropart. Phys.

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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“…For calculating this quantity, we use Ω b h 2 = 0.024 and Ω 0m h 2 = 0.14 ± 0.02. To calculate z ls we use a fitting function given in [16]:…”

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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

Alam

Sahni

Starobinsky

2007

J. Cosmol. Astropart. Phys.

116

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“…By measuring this acoustic scale at a variety of redshifts, one can infer D A (z) and H(z). The acoustic length scale can be computed as the comoving distance that the sound waves could travel from the Big Bang until recombination at z = z * (see descriptions by Hu and Sugiyama, 1996;. This is a simple integral…”

Section: General Principlesmentioning

confidence: 99%

Observational probes of cosmic acceleration

et al. 2013

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The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit "Stage IV" dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock-Paczynski effect, and direct measurements of the Hubble constant H 0 . We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over ever larger scales.

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“…These numerical solutions will manifest the interesting features we have read from the analytic solutions, particularly the feature that w φ approaches the constant tracker values in RD and MD, leaves the tracker and starts decreasing when the universe is leaving MD for SD, keeps decreasing and crosses the phantom divide in SD, and goes to negative infinity at a finite time eventually. In addition, we confront this self-potential-free teleparallel dark energy model with the observational data that are relevant to the cosmic expansion, including SNIa [14], BAO [15,16] and CMB [17,18], thereby obtaining the constraint on the sole model parameter, i.e. the non-minimal coupling constant ξ, as well as the cosmological parameters.…”

Section: Possible Evolution Patterns and Data Fittingmentioning

confidence: 99%

Teleparallel dark energy with purely non-minimal coupling to gravity

Lee

Geng

2013

Physics Letters B

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We propose the simplest model of teleparallel dark energy with purely a non-minimal coupling to gravity but no self-potential, a single model possessing various interesting features: simplicity, selfpotential-free, the guaranteed late-time cosmic acceleration driven by the non-minimal coupling to gravity, tracker behavior of the dark energy equation of state at earlier times, a crossing of the phantom divide at a late time, and the existence of a finite-time future singularity. We find the analytic solutions of the dark-energy scalar field respectively in the radiation, matter, and dark energy dominated eras, thereby revealing the above features. We further illustrate possible cosmic evolution patterns and present the observational constraint of this model obtained by numerical analysis and data fitting. PACS numbers: 95.36.+x, 04.50.Kd, 98.80.Es

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Small‐Scale Cosmological Perturbations: An Analytic Approach

Cited by 909 publications

References 31 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

Observational probes of cosmic acceleration

Teleparallel dark energy with purely non-minimal coupling to gravity

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