A redshift-magnitude formula for the universe with cosmological constant and radiation pressure

Dąbrowski, Mariusz P.; Stelmach, Jerzy

doi:10.1086/114261

Cited by 21 publications

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“…2 we present a redshift-magnitude relation (10) for brane models with dark energy (γ = −1/3). Note that the theoretical curves are very close to that of [3] which means that the dark energy cancels the positivepressure influence of the ̺ 2 term and can simulate the negative-pressure influence of the cosmological constant to cause cosmic acceleration.…”

Section: Figmentioning

confidence: 99%

“…In a flat dust (γ = 1) universe θ has the minimum value z min = 5/4. It is particularly interesting to notice that for flat brane models with Ω λ ≈ 0, Ω Λ (4) ≈ 0 the dark radiation can enlarge the minimum value of θ while the ordinary radiation lowers this value [10], i.e., z min = 1 2U Ω U − 1 + 3Ω U + 1 ≥ 5 4…”

Section: Figmentioning

confidence: 99%

“…In particular, oscillating non-singular solutions appear for dark energy γ = −1/3 [16]. In order to study observational tests we now define dimensionless observational density parameters [10,11] …”

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Brane Universes Tested by Supernovae

Godlowski

Szydłowski

Springer Proceedings in Physics

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We discuss observational constrains coming from supernovae Ia [3] imposed on the behaviour of the Randall-Sundrum models. In the case of dust matter on the brane, the difference between the best-fit general relativistic model with a Λ-term [3] and the best-fit brane models becomes detectable for redshifts z > 0.6. It is interesting that brane models predict brighter galaxies for such redshifts which is in agreement with the measurement of the z = 1.7 supernova [6] and with the New Data from the High Z Supernovae Search Team [7]. We also demonstrate that the fit to supernovae data can also be obtained, if we admit the "super-negative" dark energy p = −(4/3)̺ on the brane, where the dark energy in a way mimics the influence of the cosmological constant. It also appears that the dark energy enlarges the age of the universe which is demanded in cosmology. Finally, we propose to check for dark radiation and brane tension by the application of the angular diameter of galaxies minimum value test. The idea of brane universes has originated from Hořava and Witten [1] followed by Randall and Sundrum [2]. Brane models admit new parameters which are not present in standard cosmology (brane tension λ and dark radiation U). From the astronomical observations of supernovae Ia [3, 4] one knows that the universe is now accelerating and the best-fit model is for the 4-dimensional cosmological constant density parameter Ω Λ (4) ,0 = 0.72 and for the dust density parameter Ω m,0 = 0.28 (index "0" refers to the present moment of time). In other words, only the exotic (negative pressure) matter in standard cosmology can lead to this global effect. On the other hand, in brane models the ̺ 2 quadratic contribution in the energy density even for a small negative pressure, contributes effectively as the positive pressure, and makes brane models less accelerating. In this paper we argue that in order to avoid this problem

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Section: Figmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

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Brane Universes Tested by Supernovae

Godlowski

Szydłowski

Springer Proceedings in Physics

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“…Using the subtraction between (39a) and (39b), and then, manipulating Eqs. (38) and (37), it follows that a(T ) is a constant (a(T ) = −k/2). From Eq.…”

Section: A Schwarzschild Solutionmentioning

confidence: 99%

“…We shall describe gravitational interaction 37 by means of a fourth-rank tensor Q αβµν . We shall set up its algebraic properties and give its dynamics.…”

Section: Appendix: An Example Of Further Developments In Qm-formamentioning

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The Quasi-Maxwellian Equations of General Relativity: Applications to Perturbation Theory

2014

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A comprehensive review of the equations of general relativity in the quasi-Maxwellian (QM) formalism introduced by Jordan, Ehlers and Kundt is made. Our main interest concerns its applications to the analysis of the perturbation of standard cosmology in the Friedman-Lemaître-Robertson-Walker framework. The major achievement of the QM scheme is its use of completely gauge independent quantities. We shall see that in the QM-scheme we deal directly with observable quantities. This reveals its advantage over the old method introduced by Lifshitz et al that deals with perturbation in the standard Einstein framework. For completeness, we compare the QMscheme to the gauge-independent method of Bardeen, a procedure consisting on particular choices of the perturbed variables as a combination of gauge dependent quantities.

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Elliptic integrals for cosmological constant cosmologies

Feige

1992

Astron Nachr

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Following the discussion of some general properties and analytical formulae for cosmological models with non-zero cosmological constant, we show how the elliptic integrals for comoving distance and light travel time as function of redshift can be expressed through Legendre integrals of the first and third kind, for which standard implementations are readily available. Observational properties are then illustrated for selected but typical models using the previously derived formulae.Key words: cosmology -elliptic integrals -cosmological constant A A A subject classification: 161 1. I n t r o d u c t i o nThe 'standard model' of cosmology assumes a zero cosmological constant. There are controversial assessments on this theme; the fact that constraints for the cosmological constant provided by particle physics are weak in cosmological terms makes it easy to introduce it, whenever another free parameter seems to be required. Critics of this effect tend to discard it from their considerations completely. Also, the exclusion of the cosmological constant and related model parameters (Sahni et al. 1992) from simulations is often due to the computational difficulties they pose.Here we give a detailed outline of the mathematical transformations involved in expressing cosmological dependencies through standard elliptic integrals and thus provide a basis to evaluate the observational effects of a particular value of the cosmological constant. Previous papers on the subject usually failed to present this process in a way which is reproducible by non-experts and/or lacked completeness: Kaufman and Schiicking (1971), Kaufman (1971), Edwards (1972, Coquereaux and Grossmann (1982), Dabrowski and Stelmach (1986a), Dabrowski and Stelmach (1986b).T h e work described in this paper is part of the Muenster Redshift Project (MRSP) and is currently being extended to include more general models as described, e.g. by Sahni et al. (1992). 2. Cosmic dynamicsFirst we introduce the cosmological parameters and equations. More in-depth discussions of relativistic cosmology can be found in standard books by Weinberg (1972), Rindler (1977), Harrison (1981. Reviews covering the cosmological constant are given by Felten (1986) and, in more detail, by Weinberg (1989).Because of the equivalence of space and time, definitions of quantities with the same name often differ by the factor velocity of light. More confusing is the fact t h a t the same quantities are sometimes referred t o by different names. By Coquereaux and Grossmann (1982), e.g., in an extensive paper on cosmology with h-term, the quantity introduced by us as comoving distance x is named conformal time. T h e time thus defined and the light travel time t discussed later can not easily be transformed into each other. T h e notation used in this work follows recent publications.T h e assumption of homogeneity and isotropy of the universe leads to a metric, which is invariant and independent of direction in all points of space and varies with time in the same way everywhere. This leads t...

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A redshift-magnitude formula for the universe with cosmological constant and radiation pressure

Cited by 21 publications

References 0 publications

Brane Universes Tested by Supernovae

Brane Universes Tested by Supernovae

The Quasi-Maxwellian Equations of General Relativity: Applications to Perturbation Theory

Elliptic integrals for cosmological constant cosmologies

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