Deceleration Parameter

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Binaya K Bishi - One of the best experts on this subject based on the ideXlab platform.

  • lrs bianchi type i cosmological model with constant Deceleration Parameter in f r t gravity
    International Journal of Geometric Methods in Modern Physics, 2017
    Co-Authors: Binaya K Bishi, P K Sahoo, S K J Pacif, G P Singh
    Abstract:

    A spatially homogeneous anisotropic LRS Bianchi type-I cosmological model is studied in f(R,T) gravity with a special form of Hubble's Parameter, which leads to constant Deceleration Parameter. The Parameters involved in the considered form of Hubble Parameter can be tuned to match, our models with the ΛCDM model. With the present observed value of the Deceleration Parameter, we have discussed physical and kinematical properties of a specific model. Moreover, we have discussed the cosmological distances for our model.

  • bulk viscous cosmological model in brans dicke theory with new form of time varying Deceleration Parameter
    Advances in High Energy Physics, 2017
    Co-Authors: G P Singh, Binaya K Bishi
    Abstract:

    We have presented FRW cosmological model in the framework of Brans-Dicke theory. This paper deals with a new proposed form of Deceleration Parameter and cosmological constant . The effect of bulk viscosity is also studied in the presence of modified Chaplygin gas equation of state ( ). Furthermore, we have discussed the physical behaviours of the models.

  • anisotropic cosmological models in f r t gravity with variable Deceleration Parameter
    International Journal of Geometric Methods in Modern Physics, 2017
    Co-Authors: P K Sahoo, Binaya K Bishi
    Abstract:

    The objective of this work enclosed with the study of spatially homogeneous anisotropic Bianchi type-I universe in f(R,T) gravity (where R is the Ricci scalar and T is the trace of stress energy momentum tensor) in two different cases viz. f(R,T) = R + 2f(T) and f(R,T) = f1(R) + f2(T) with bulk viscosity matter content. In this study, we consider a time varying Deceleration Parameter (DP), which generates an accelerating universe to obtain the exact solution of the field equations. The physical and kinematical properties of both the models are discussed in detail for the future evolution of the universe. We have explored the nature of WEC, DEC, SEC and energy density for both the cases. We have found that both the models, with bulk viscosity matter component, show an acceleration of the universe. We have also shown that the cosmic jerk Parameter is compatible with the three kinematical data sets.

  • variable Deceleration Parameter and dark energy models
    International Journal of Geometric Methods in Modern Physics, 2016
    Co-Authors: Binaya K Bishi
    Abstract:

    This paper deals with the Bianchi type-III dark energy model and equation of state Parameter in a first class of f(R,T) gravity. Here, R and T represents the Ricci scalar and trace of the energy momentum tensor, respectively. The exact solutions of the modified field equations are obtained by using (i) linear relation between expansion scalar and shear scalar, (ii) linear relation between state Parameter and skewness Parameter and (iii) variable Deceleration Parameter. To obtain the physically plausible cosmological models, the variable Deceleration Parameter with the suitable substitution leads to the scale factor of the form a(t) = [sinh(αt)] 1 n, where α and n > 0 are arbitrary constants. It is observed that our models are accelerating for 0 1, transition phase from Deceleration to acceleration. Further, we have discussed physical properties of the models.

  • bianchi type v bulk viscous cosmic string in gravity with time varying Deceleration Parameter
    Advances in High Energy Physics, 2015
    Co-Authors: Binaya K Bishi, K L Mahanta
    Abstract:

    We study the Bianchi type-V string cosmological model with bulk viscosity in theory of gravity by considering a special form and linearly varying Deceleration Parameter. This is an extension of the earlier work of Naidu et al., 2013, where they have constructed the model by considering a constant Deceleration Parameter. Here we find that the cosmic strings do not survive in both models. In addition we study some physical and kinematical properties of both models. We observe that in one of our models these properties are identical to the model obtained by Naidu et al., 2013, and in the other model the behavior of these Parameters is different.

Suresh Kumar - One of the best experts on this subject based on the ideXlab platform.

  • probing kinematics and fate of the universe with linearly time varying Deceleration Parameter
    European Physical Journal Plus, 2014
    Co-Authors: Ozgur Akarsu, Tekin Dereli, Suresh Kumar, Lixin Xu
    Abstract:

    The parametrizations q = q 0+q 1 z and q = q 0+q 1(1 − a/a 0) (Chevallier-Polarski-Linder parametrization) of the Deceleration Parameter, which are linear in cosmic redshift z and scale factor a , have been frequently utilized in the literature to study the kinematics of the Universe. In this paper, we follow a strategy that leads to these two well-known parametrizations of the Deceleration Parameter as well as an additional new parametrization, q = q 0+q 1(1 − t/t 0), which is linear in cosmic time t. We study the features of this linearly time-varying Deceleration Parameter in contrast with the other two linear parametrizations. We investigate in detail the kinematics of the Universe by confronting the three models with the latest observational data. We further study the dynamics of the Universe by considering the linearly time-varying Deceleration Parameter model in comparison with the standard ΛCDM model. We also discuss the future of the Universe in the context of the models under consideration.

  • Observational constraints on the kinematics and the fate of the Universe through linearly varying Deceleration Parameter laws
    2013
    Co-Authors: Ozgur Akarsu, Tekin Dereli, Suresh Kumar, Lixin Xu
    Abstract:

    The Deceleration Parameter being poorly known by observations but a key Parameter in cosmology has been frequently investigated with observational data through its model independent phenomenological parametrizations in terms of cosmic redshift or scale factor. In this paper, we study linearly varying Deceleration Parameter in terms of cosmic time t (LVDPt) with the companion linearly varying Deceleration Parameter in terms of cosmic redshift z (LVDPz) and in terms of cosmic scale factor a (LVDPa). We investigate in detail the kinematics and the fate of the Universe by confronting the three LVDP laws with the latest observational data from H(z) compilation (25 data points) and SN Ia Union2.1 compilation (580 data points). The study reveals that the LVDPt law is superior than LVDPz and LVDPa laws in many aspects. In particular, the goodness of fit to the observational data is found to be the best for the LVDPt law. The kinematics and dynamics (assuming general relativity) of the Universe is further studied by considering the LVDPt law in

  • anisotropic bianchi type i models with constant Deceleration Parameter in general relativity
    Astrophysics and Space Science, 2007
    Co-Authors: Suresh Kumar, C P Singh
    Abstract:

    A special law of variation for Hubble’s Parameter is presented in a spatially homogeneous and anisotropic Bianchi type-I space-time that yields a constant value of Deceleration Parameter. Using the law of variation for Hubble’s Parameter, exact solutions of Einstein’s field equations are obtained for Bianchi-I space-time filled with perfect fluid in two different cases where the universe exhibits power-law and exponential expansion. It is found that the solutions are consistent with the recent observations of type Ia supernovae. A detailed study of physical and kinematical properties of the models is carried out.

  • bianchi type ii space times with constant Deceleration Parameter in self creation cosmology
    Astrophysics and Space Science, 2007
    Co-Authors: C P Singh, Suresh Kumar
    Abstract:

    The properties of locally rotationally symmetric Bianchi type-II perfect fluid space-times are analyzed in Barber’s second self-creation theory by using a special law of variation for Hubble’s Parameter that yields a constant value of Deceleration Parameter. By assuming the equation of state p=γρ, many new solutions are obtained for different era—Zel’dovich, radiation, vacuum and vacuum energy dominated. The solutions with power-law and exponential expansion are discussed. A detailed study of geometrical and physical Parameters is carried out. The nature of singularity is also clarified in each case.

  • bianchi type ii cosmological models with constant Deceleration Parameter
    International Journal of Modern Physics D, 2006
    Co-Authors: C P Singh, Suresh Kumar
    Abstract:

    A special law of variation for Hubble's Parameter in anisotropic space–time models that yields a constant value of the Deceleration Parameter is presented. Also, a spatially homogeneous and anisotropic but locally rotationally symmetric (LRS) Bianchi type-II cosmological model is studied with a perfect fluid and constant Deceleration Parameter. Assuming the equation of state p = γρ, where 0≤γ≤1, and using a special law of variation for the Hubble Parameter, we are able to construct many new solutions to Einstein's field equations of LRS Bianchi type-II for four different physical models (dust, radiation, Zel'dovich and vacuum). We discuss the solutions with power-law and exponential expansion and examine a particular class of models. A detailed study of kinematic, geometrical and observational properties is carried out.

Anirudh Pradhan - One of the best experts on this subject based on the ideXlab platform.

  • tsallis holographic dark energy in frw universe with time varying Deceleration Parameter
    New Astronomy, 2019
    Co-Authors: Archana Dixit, Umesh Kumar Sharma, Anirudh Pradhan
    Abstract:

    Abstract By considering the time-varying Deceleration Parameter (DP), we have investigated Tsallis holographic dark energy (THDE), infrared cut-off with the Hubble horizon proposed by Tavayef, et al. (2018) in the framework of Friedmann Robertson Walker universe. The proposed THDE model describes that the universe is in an accelerating expansion mode. Interestingly enough, the EoS Parameter in our model is representing the outstanding evolution of the universe as, the quintessence era ( ω T ≥ − 1 ), phantom era ( ω T − 1 ), according to the value of dimensionless Parameter δ. To analyze the different structure of the model, we try to accommodate the two perspectives of (DE) by reconstructing the scalar field potential, which depicts the accelerated expansion at present. We examine the validity of the model by drawing the statefinder Parameters and comparing them with the recent observational outcomes of cosmography.

  • anisotropic bianchi i cosmological models in string cosmology with variable Deceleration Parameter
    arXiv: General Physics, 2012
    Co-Authors: Chanchal Chawla, R. K. Mishra, Anirudh Pradhan
    Abstract:

    The present study deals with spatially homogeneous and anisotropic Bianchi-I cosmological model representing massive strings. The energy-momentum tensor, as formulated by Letelier (Phys. Rev. D 28: 2414, 1983) has been used to construct massive string cosmological model for which we assume that the expansion scalar in the model is proportional to one of the components of shear tensor. The Einstein's field equations have been solved by considering time dependent Deceleration Parameter which renders the scale factor $a = (\sinh(\alpha t))^{\frac{1}{n}}$, where $\alpha$ and $n$ are constants. It has been detected that, for $n > 1$, the presented model has a transition of the universe from the early decelerated phase to the recent accelerating phase at present epoch while for $0 < n \leq 1$, this describes purely accelerating universe which is consistent with recent astrophysical observations. Moreover, some physical and geometric properties of the model along with physical acceptability of the solutions have been also discussed in detail.

  • accelerating dark energy models in bianchi type v space time with time dependent Deceleration Parameter
    Electronic Journal of Theoretical Physics, 2012
    Co-Authors: Anirudh Pradhan, Hassan Amirhashchi, Hishamuddin Zainuddin
    Abstract:

    Some new exact solutions of Einstein's field equations have emerged in a spatially homogeneous and anisotropic Bianchi type-V space-time with minimally interacting perfect fluid and anisotropic dark energy (DE) components, which has dynamic equation of state (EoS). We consider Bianchi type-V space-time, introducing three different skewness Parameters along spatial directions to quantify deviation of pressure from isotropy. To obtain the deterministic solution we choose the scale factor a(t )= √ t n e t , which yields a time-dependent Deceleration Parameter (DP). We find that the time dependent value of Deceleration Parameter is reasonable for the present day universe which yields a transition of the universe from the early decelerating phase to the recent accelerating phase. For different values of n, we can generate a class of physically viable DE models. It is found that quintessence model is suitable for describing the present evolution of the universe. The physical and geometric properties of spatially homogeneous and anisotropic cosmological models are discussed.

  • anisotropic bianchi i cosmological model in string cosmology with variable Deceleration Parameter
    Romanian Journal of Physics, 2012
    Co-Authors: Chanchal Chawla, Anirudh Pradhan, R. K. Mishra
    Abstract:

    The present study deals with spatially homogeneous and anisotropic Bianchi type I cosmological model representing massive strings. The energy-momentum tensor, as formulated by Letelier [Phys. Rev. D 28, 2414 (1983)] has been used to construct massive string cosmological model for which we assume that the expansion scalar in the model is proportional to one of the components of shear tensor. The Einstein’s field equations have been solved by considering time dependent Deceleration Parameter which renders the scale factor a = (sinh(t )) 1 n, where and n are constants. It has been detected that, for n > 1, the presented model universe exhibits phase transition from early decelerated phase to accelerating phase at present epoch while for 0

  • bianchi type i anisotropic dark energy models with constant Deceleration Parameter
    arXiv: General Physics, 2010
    Co-Authors: Anirudh Pradhan, Hassan Amirhashchi, Bijan Saha
    Abstract:

    New dark energy models in anisotropic Bianchi type-I (B-I) space-time with variable EoS Parameter and constant Deceleration Parameter have been investigated in the present paper. The Einstein's field equations have been solved by applying a variation law for generalized Hubble's Parameter in B-I space-time. The variation law for Hubble's Parameter generates two types of solutions for the average scale factor, one is of power-law type and other is of the exponential form. Using these two forms, Einstein's field equations are solved separately that correspond to expanding singular and non-singular models of the universe respectively. The equation of state (EoS) Parameter $\omega$ is found to be time dependent and its existing range for this model is in good agreement with the recent observations of SNe Ia data, SNe Ia data (with CMBR anisotropy) and galaxy clustering statistics. The cosmological constant $\Lambda$ is found to be a decreasing function of time and it approaches a small positive value at late time (i.e. the present epoch) which is corroborated by results from recent supernovae Ia observations.

D. R. K. Reddy - One of the best experts on this subject based on the ideXlab platform.

S. Umadevi - One of the best experts on this subject based on the ideXlab platform.

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