Varying-G cosmology with type Ia supernovae

Dungan, R.; Prosper, H.

doi:10.1119/1.3486585

Cited by 13 publications

(10 citation statements)

References 21 publications

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“…giving the dependence of distance modulus in terms of the redshift. Using forms of Ω (1) and Ω (2) and integrating the relation ( 9) and using equation (7), one can obtain this dependence. The result is:…”

Section: λCdm Vs Slow-varying-gmentioning

confidence: 99%

Notes on the compatibility of type Ia supernovae data and varying--$G$ cosmology

Shojai,

Shojai

2013

Preprint

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Observational data for type Ia supernovae, shows that the expansion of the universe is accelerated. This accelerated expansion can be described by a cosmological constant or by dark energy models like quintessence. An interesting question may be raised here. Is it possible to describe the accelerated expansion of universe using varying-G cosmological models? Here we shall show that the price for having accelerated expansion in slow-varying-G models (in which the dynamical terms of G are ignored) is to have highly non-conserved matter and also that it is in contradiction with other data.

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Section: λCdm Vs Slow-varying-gmentioning

confidence: 99%

Notes on the compatibility of type Ia supernovae data and varying--$G$ cosmology

Shojai,

Shojai

2013

Preprint

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“…Supernovae have also been very useful as approximately standard candles in cosmology, and such studies can also be adapted to constrain a combination of fundamental constant variations [90,91,92,93]. Like other stellar sources, there is a dependence on α −1/2 g in the evolutionary timescale (see e.g.…”

Section: Large-scale Structure and Supernovaementioning

confidence: 99%

Dimensionless cosmology

Narimani

Moss

Scott

2012

Astrophys Space Sci

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Although it is well known that any consideration of the variations of fundamental constants should be restricted to their dimensionless combinations, the literature on variations of the gravitational constant $G$ is entirely dimensionful. To illustrate applications of this to cosmology, we explicitly give a dimensionless version of the parameters of the standard cosmological model, and describe the physics of Big Bang Neucleosynthesis and recombination in a dimensionless manner. The issue that appears to have been missed in many studies is that in cosmology the strength of gravity is bound up in the cosmological equations, and the epoch at which we live is a crucial part of the model. We argue that it is useful to consider the hypothetical situation of communicating with another civilization (with entirely different units), comparing only dimensionless constants, in order to decide if we live in a Universe governed by precisely the same physical laws. In this thought experiment, we would also have to compare epochs, which can be defined by giving the value of any {\it one} of the evolving cosmological parameters. By setting things up carefully in this way one can avoid inconsistent results when considering variable constants, caused by effectively fixing more than one parameter today. We show examples of this effect by considering microwave background anisotropies, being careful to maintain dimensionlessness throughout. We present Fisher matrix calculations to estimate how well the fine structure constants for electromagnetism and gravity can be determined with future microwave background experiments. We highlight how one can be misled by simply adding $G$ to the usual cosmological parameter set

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“…Of course G also determines the expansion of the universe so the supernova flux we can expect to receive depends also on the entire history of this constant, G(t), between explosion and detection. Analyses of SNIa data taking into account both supernova luminosities and light propagation have been performed [8,9,10,11] yielding limits on the time variation of G, generally supposing that all other fundamental constants are time-independent.…”

Section: Introductionmentioning

confidence: 99%

Dimensionless constants and cosmological measurements

Rich

2013

Preprint

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The laws of physics have a set of fundamental constants, and it is generally admitted that only dimensionless combinations of constants have physical significance. These combinations include the electromagnetic and gravitational fine structure constants, α = e 2 /4πǫ 0 hc and α G = Gm 2 p /hc, along with the ratios of elementaryparticles masses. Cosmological measurements clearly depend on the values of these constants in the past and can therefore give information on their time dependence if the effects of time-varying constants can be separated from the effects of cosmological parameters. The latter can be eliminated by using pairs of redundant measurements and here we show how such pairs conspire to give information only on dimensionless combinations of constants. Among other possibilities, we will use distance measurements based on Baryon Acoustic Oscillations (BAO) and on type Ia supernova. The fact that measurements yield information only on dimensionless combinations is traced to the fact that distances between co-moving points expand following the same function of time that governs the redshift of photon wavelengths.

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Varying-G cosmology with type Ia supernovae

Cited by 13 publications

References 21 publications

Notes on the compatibility of type Ia supernovae data and varying--$G$ cosmology

Notes on the compatibility of type Ia supernovae data and varying--$G$ cosmology

Dimensionless cosmology

Dimensionless constants and cosmological measurements

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