Gravitationally influenced particle creation models and late-time cosmic acceleration

Pan, Supriya; Pal, Barun Kumar; Pramanik, Souvik

doi:10.1142/s0219887818500421

Cited by 19 publications

(12 citation statements)

References 90 publications

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“…where a(t) is the scale factor of the universe; k is the spatial curvature which for its three distinct values, namely, 0, −1, +1, respectively represent a spatially flat, open 1 In this connection we recall an equivalent cosmological theory known gravitationally induced particle creation theory [55,56,57,58,59,60,61,62,63,64,65,66,67,68] which is equivalent to the bulk viscous theory at the level of equations but from the thermodynamical point of view both are theories are distinct [69]. and a closed universe.…”

Section: The Background and Perturbation Equations For A Viscous Univmentioning

confidence: 99%

Challenging bulk viscous unified scenarios with cosmological observations

et al. 2019

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In a spatially flat Friedmann-Lemaître-Robertson-Walker universe, we investigate a unified cosmic fluid scenario endowed with bulk viscosity in which the coefficient of the bulk viscosity has a power law evolution. The power law in the bulk viscous coefficient is a general case in this study which naturally includes several choices as special cases. Considering such a general bulk viscous scenario, in the present work we have extracted the observational constraints using the latest cosmological datasets and examine their behaviour at the level of both background and perturbations. From the observational analyses, we find that a non-zero bulk viscous coefficient is always favored and some of the models in this series are able to weaken the current tension on H0 for some dataset. At the level of perturbations, the models are very much sensitive to their free parameters. We find that the matter power spectra show an unusual blowing up for sufficient strength of the bulk viscous coefficient.

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Section: The Background and Perturbation Equations For A Viscous Univmentioning

confidence: 99%

Challenging bulk viscous unified scenarios with cosmological observations

et al. 2019

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“…Usually there are two distinct approaches to describe such accelerating expansion -one route is through the modifications of the matter sector in the context of Einstein gravity [5,6,7], and the other way around is to modify the Einstein's gravitational theories [8,9,10,11,12,13,14,15,16] which leads to some extra geometrical terms (alternatively known as geometrical dark energy fluids in order to make a difference between the accelerating effects coming from the matter modifications or geometry modifications). Apart from above two approaches there is another alternative to describe this accelerating universe -the gravitational particle production mechanism, see [17,18,19,20,21,22,23,24,25,26] and references therein. However, overall, the actual dynamics of these mysterious components are unknown, but thanks to the recent observational evidences, we have an estimate of such dark fluids.…”

Section: Introductionmentioning

confidence: 99%

Constraints on quintessence scalar field models using cosmological observations

Yang

Shahalam

Pal³

et al. 2019

Phys. Rev. D

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We consider a varieties of quintessence scalar field models in a homogeneous and isotropic geometry of the universe with zero spatial curvature aiming to provide stringent constraints using a series of cosmological data sets, namely, the cosmic microwave background observations (CMB), baryon acoustic oscillations (BAO), joint light curve analysis (JLA) from supernovae type Ia, redshift space distortions (RSD), and the cosmic chronometers (CC). From the qualitative evolution of the models, we find all of them are able to execute a fine transition from the past decelerating phase to the presently accelerating expansion where in addition, the equation of state of the scalar field (also the effective equation of state) might be close to that of the ΛCDM cosmology depending on its free parameters. From the observational analyses, we find that the scalar field parameters are unconstrained irrespective of all the observational datasets. In fact, we find that the quintessence scalar field models are pretty much determined by the CMB observations since any of the external datasets such as BAO, JLA, RSD, CC does not add any constraining power to CMB. Additionally, we observe a strong negative correlation between the parameters H0 (present value of the Hubble parameter), Ωm0 (density parameter for the matter sector, i.e., cold dark matter plus baryons) exists, while no correlation between H0, and σ8 (amplitude of the matter fluctuation) are not correlated. We also comment that the present models are unable to reconcile the tension on H0. Finally, we conclude our work with the Bayesian analyses which report that the non-interacting ΛCDM model is preferred over all the quintessence scalar field models.

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“…which looks like the particle creation, bulk viscosity or varying vacuum theories [60][61][62][63][64][65][66]. Positive values of B φ indicate particle annihilation while negative values of B φ indicate particle creation.…”

Section: Einstein-aether Scalar Field Cosmologymentioning

confidence: 99%

Analytic solutions in Einstein-aether scalar field cosmology

Paliathanasis¹,

León²

2020

Eur. Phys. J. C

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In the context of Einstein-aether scalar field cosmology we solve the field equations and determine exact and analytic solutions. In particular, we consider a model proposed by Kanno and Soda where the aether and the scalar fields interact through the aether coefficient parameters, which are promoted to be functions of the scalar field. For this model, we write the field equations by using the minisuperspace approach and we determine the scalar field potentials which leads to Liouville-integrable systems. We solve the field equations for five families of scalar field potentials and, whether it is feasible, we write down the analytic solutions by using closed-form functions.

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Gravitationally influenced particle creation models and late-time cosmic acceleration

Cited by 19 publications

References 90 publications

Challenging bulk viscous unified scenarios with cosmological observations

Challenging bulk viscous unified scenarios with cosmological observations

Constraints on quintessence scalar field models using cosmological observations

Analytic solutions in Einstein-aether scalar field cosmology

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