Constraints on the Generalized Chaplygin Gas Model from Recent Supernova Data and Baryonic Acoustic Oscillations

Wu, Puxun; Yu, Hongwei

doi:10.1086/510768

Cited by 23 publications

(23 citation statements)

References 56 publications

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“…(4), we show the results from the lookback time-redshift (LT) data, which is very similar to the results obtained from the Sne Ia data [13]. The best-fit values are A s = 0.47 and α = −0.85.…”

Section: For the Gcg Model E(p) In The Friedmann Equation Now Has Thsupporting

confidence: 78%

Testing the (generalized) Chaplygin gas model with the lookback time-redshift data

2009

J. Cosmol. Astropart. Phys.

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The Chaplygin gas (CG) and the generalized Chaplygin gas (GCG) models, proposed as candidates of the unified dark matter-dark energy (UDME), are tested with the look-back time (LT) redshift data. We find that the LT data only give a very weak constraint on the model parameter. However, by combing the LT with the baryonic acoustic oscillation peak, we obtain, at the 95.4% confidence level, 0.68 ≤ A c ≤ 0.82 and 0.59 ≤ h ≤ 0.65 for the CG model , and 0.67 ≤ A s ≤ 0.89 and −0.29 ≤ α ≤ 0.61 for the GCG model. This shows that both the CG and the GCG are viable as a candidate of UDME. Within the GCG model, we also find that the Chaplygin gas model (α = 1) is ruled out by these data at the 99.7% confidence level.

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Section: For the Gcg Model E(p) In The Friedmann Equation Now Has Thsupporting

confidence: 78%

Testing the (generalized) Chaplygin gas model with the lookback time-redshift data

2009

J. Cosmol. Astropart. Phys.

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“…This is in agreement with previous, independent fits (e.g. [4] ) including the most recent ones [18]. We can say that our combined analysis constrains the generalized Chaplygin gas scenario to cases effectively equivalent to ΛCDM model.…”

Section: +072supporting

confidence: 92%

Cosmic Equation of state from Strong Gravitational Lensing Systems

Malec¹

2011

Proceedings of 25th Texas Symposium on Relativistic Astrophysics — PoS(Texas 2010)

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Here we present the joint analysis of five dark energy models using the data from Type Ia Supernovae (data from recent Union2 compilation), Cosmic Microwave Background (CMB) shift parameter R (WMAP7 data), Baryon Acoustic Oscillation (BAO) and strongly gravitationally lensed quasar-galaxy systems (combined data sets from SLACS and LSD surveys). These different tests falls into two distinct classes. The first one makes use of the angular diameter distance, and refers to the so called standard rulers. The second uses the luminosity distance and then we deal with standard candles. The two distance concepts, although theoretically related to each other, in practice have different systematic uncertainties and different parameter degeneracies. Hence their joint analysis is more restrictive in the parameter space. We have considered ΛCDM model, two Quintessence scenarios (with constant and variable equation of state), generalized Chaplygin gas and braneworld (Dvali, Gabadagdze, Porrati -DGP) model. The best fits we obtained for the model parameters in joint analysis turned out to prefer cases effectively equivalent to ΛCDM model. Our findings are in agreement with parallel studies performed by other authors on different sets of diagnostic probes. We also tried to answer question: "Which model is the best?" with the aid of two informationtheoretic criteria: the Akaike Criterion (AIC) and Bayesian Information Criterion(BIC). It lead us to similar conclusion that the concordance model ΛCDM is clearly preferred in joint analysis. The quintessence (both having constant or time varying equation of state), and Chaplygin gas get considerably less support from the data while the brane world (DGP) scenario is practically ruled out.

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“…Alternatively, one may leave A as a free parameter to be determined by best-fitting models to observations (e.g., Wu & Yu 2007), in which case one obtains 0.6ρ…”

Section: Basic Propertiesmentioning

confidence: 99%

Unified dark matter: constraints from galaxies and clusters

El-Zant

2015

Mon. Not. R. Astron. Soc.

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Unified dark matter models are appealing in that they describe the dark sector in terms of a single component. They however face problems when attempting to account for structure formation: in the linear regime, density fluctuations can become Jeans stable and oscillate rather than collapse, though it is possible that this difficulty may be circumvented by invoking nonlinear clustering. Here we examine the behaviour in the fully nonlinear regime, of collapsed objects that should mimic standard dark matter haloes. It is shown that the pressure gradient associated with the unified dark matter fluid should be significant in the outer parts of galaxies and clusters, and its effects obervable. In this case, no flat or falling rotation curve is possible for any (barotropic) equation of state with associated sound speed decreasing with density (a necessary condition if the fluid is to behave as pressureless matter at high density). The associated density profile is therefore also incompatible with that inferred in the outer part of clusters. For the prototypical case of the generalised Chaplygin gas, it is shown that this limits the values of the equation of state index α that are compatible with observations to α 0.0001 or α 2. This is in line from what is deduced from linear analysis. More generally, from the expected properties of dark matter haloes, constraints on the sound speed are derived. For the particular case of the generalised Chaplygin gas, this further constrains the index to α 10 −9 or α 6.7. For a unified dark matter fluid to mimic dark halo properties, therefore, it needs to have an equation of state such that the pressure gradients are either minimal or which decrease fast enough so as to be negligible at densities characteristic of the outer parts of haloes.

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Constraints on the Generalized Chaplygin Gas Model from Recent Supernova Data and Baryonic Acoustic Oscillations

Cited by 23 publications

References 56 publications

Testing the (generalized) Chaplygin gas model with the lookback time-redshift data

Testing the (generalized) Chaplygin gas model with the lookback time-redshift data

Cosmic Equation of state from Strong Gravitational Lensing Systems

Unified dark matter: constraints from galaxies and clusters

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