[ITAL]BVRI[/ITAL] Light Curves for 22 Type I[CLC]a[/CLC] Supernovae

Riess, Adam G.; Kirshner, R.; Schmidt, B. P.; Jha, Saurabh W.; Challis, P.; Garnavich, P.; Esin, A. A.; Carpenter, Chris; Grashius, Randy; Schild, Rudolph E.; Berlind, P.; Huchra, J. P.; Prosser, Charles F.; Falco, E.; Benson, P. J.; Briceño, César; Brown, Warren R.; Caldwell, Nelson; Dell’Antonio, Ian; Filippenko, A. V.; Goodman, Alyssa A.; Grogin, Norman A.; Groner, Ted; Hughes, John P.; Green, Paul; Jansen, Rolf A.; Kleyna, Jan; Luu, Jane; Macri, Lucas M.; McLeod, B. A.; McLeod, Kim K.; McNamara, B. R.; McLean, B.; Milone, Alejandra A. E.; Mohr, J. J.; Moraru, D.; Peng, Chien Y.; Peters, J.; Prestwich, Andrea; Stanek, K. Z.; Szentgyörgyi, Á.; Zhao, Ping

doi:10.1086/300738

Cited by 632 publications

(335 citation statements)

References 67 publications

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“…IV, we probe a more plausible and simple model, namely, f (R, T ) = R + c 1 √ −T , in a non-flat background space-time. 3 This interesting model has some similarity to the models with time-dependent cosmological constant. One can interpret the term √ −T as a cosmological constant depending on the matter that implicitly depends on time.…”

Section: Introductionmentioning

confidence: 75%

Cosmological and solar system consequences off(R,T)gravity models

2014

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To find more deliberate f (R, T ) cosmological solutions, we proceed our previous paper further by studying some new aspects of the considered models via investigation of some new cosmological parameters/quantities to attain the most acceptable cosmological results. Our investigations are performed by applying the dynamical system approach. We obtain the cosmological parameters/quantities in terms of some defined dimensionless parameters that are used in constructing the dynamical equations of motion. The investigated parameters/quantities are the evolution of the Hubble parameter and its inverse, the "weight function", the ratio of the matter density to the dark energy density and its time variation, the deceleration, the jerk and the snap parameters, and the equation-of-state parameter of the dark energy. We numerically examine these quantities for two general models R + αR −n + √ −T and R log [αR] q + √ −T . All considered models have some inconsistent quantities (with respect to the available observational data), except the model with n = −0.9 which has more consistent quantities than the other ones. By considering the ratio of the matter density to the dark energy density, we find that the coincidence problem does not refer to a unique cosmological event, rather, this coincidence also occurred in the early universe. We also present the cosmological solutions for an interesting model R+c1 √ −T in the non-flat FLRW metric. We show that this model has an attractor solution for the late times, though with w (DE) = −1/2. This model indicates that the spatial curvature density parameter gets negligible values until the present era, in which it acquires the values of the order 10 −4 or 10 −3 . As the second part of this work, we consider the weak-field limit of f (R, T ) gravity models outside a spherical mass immersed in the cosmological fluid. We have found that the corresponding field equations depend on the both background values of the Ricci scalar and the background cosmological fluid density. As a result, we attain the parametrized post-Newtonian (PPN) parameter for f (R, T ) gravity and show that this theory can admit the experimentally acceptable values of this parameter. As a sample, we present the PPN gamma parameter for general minimal power law models, in particular, the model R + c1 √ −T .

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Section: Introductionmentioning

confidence: 75%

Cosmological and solar system consequences off(R,T)gravity models

2014

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“…The simple fact that, observationally, q 0 is negative [24,[46][47][48], renders j 0 positive in the said model; i.e., cosmic acceleration should be increasing nowadays.…”

Section: The Jerk Parametermentioning

confidence: 94%

Strategies to Ascertain the Sign of the Spatial Curvature

Ferreira

Pavón

2016

Universe

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Abstract:The second law of thermodynamics, in the presence of gravity, is known to hold at small scales, as in the case of black holes and self-gravitating radiation spheres. Using the Friedmann-Lemaître-Robertson-Walker metric and the history of the Hubble factor, we argue that this law also holds at cosmological scales. Based on this, we study the connection between the deceleration parameter and the spatial curvature of the metric, Ω k , and set limits on the latter, valid for any homogeneous and isotropic cosmological model. Likewise, we devise strategies to determine the sign of the spatial curvature index k. Finally, assuming the lambda cold dark matter model is correct, we find that the acceleration of the cosmic expansion is increasing today.

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“…It is interesting to note that the models represent accelerating universes for −1 < < −1/2 and conformed to the well known fact that the scalar field and the bulk viscosity will play a vital role in getting an accelerated universe. Also recent observations of type Ia supernovae (SN Ia), Perlmutter et al [27] and Riess et al [28][29][30] proved that the decelerating parameter of the universe is in the range −1 ≤ ≤ 0, and the present day universe is undergoing accelerated expansion. Finally, we noticed that the presence of scalar field in BransDicke theory does not affect the geometry of the spacetime but changes the matter distribution in comparison with Einstein theory, and as a special case, it is always possible to obtain axially symmetric string cosmological model with bulk viscosity in general relativity.…”

Section: Discussionmentioning

confidence: 99%

Axially Symmetric Bulk Viscous String Cosmological Models in GR and Brans-Dicke Theory of Gravitation

Rao

Neelima

2013

ISRN Astronomy and Astrophysics

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Axially symmetric string cosmological models with bulk viscosity in Brans-Dicke (1961) and general relativity (GR) have been studied. The field equations have been solved by using the anisotropy feature of the universe in the axially symmetric space-time. Some important features of the models, thus obtained, have been discussed. We noticed that the presence of scalar field does not affect the geometry of the space-time but changes the matter distribution, and as a special case, it is always possible to obtain axially symmetric string cosmological model with bulk viscosity in general relativity.

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[ITAL]BVRI[/ITAL] Light Curves for 22 Type I[CLC]a[/CLC] Supernovae

Cited by 632 publications

References 67 publications

Cosmological and solar system consequences off(R,T)gravity models

Cosmological and solar system consequences off(R,T)gravity models

Strategies to Ascertain the Sign of the Spatial Curvature

Axially Symmetric Bulk Viscous String Cosmological Models in GR and Brans-Dicke Theory of Gravitation

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