[Submitted on 26 Oct 2022]

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    Abstract: We attempt to model a present time accelerating universe, in the framework of
    FLRW space-time using field equations of f(R,T) gravity and taking $f(R,T) = R
    + 2 \lambda T$, $\lambda$ being an arbitrary constant. For this, terms
    containing $\lambda$ in the field equation are assumed as a source of energy
    producing negative pressure. Our model is a novel one in the sense that the
    $\lambda$ parameter develops a fluid whose equation of state is parameterized.
    The model parameters, present values of density, Hubble and deceleration
    parameters are estimated statistically to arrive at physically viable
    cosmology. We consider three types of observational data set: $46$ Hubble
    parameter data set, SNe Ia $715$ data sets of distance modulus and apparent
    magnitude and 66 Pantheon data set (the latest compilation of SN Ia 40 bined
    plus 26 high redshift apparent magnitude $m_b$ data set in the redshift range
    $0.014 \leq z \leq 2.26 $. These data are compared with theoretical results
    through the $ \chi^2 $ statistical test. The universe model exhibits phase
    transition from decelerating to accelerating one. We have calculated transional
    red shifts and time for the data sets. Our estimated results for the present
    values of various model parameters such Hubble , deceleration etc. are found as
    per expectations and surveys. We get a very interesting result from estimations
    that at present, the value of density $\rho_0$ is $\simeq 1.5 \rho_c $. The
    critical density is estimated as $\rho_c\simeq 1.88~ h_0^2~10^{-29}~gm/cm^3 $
    in the literature. The higher value of present density is attributed to the
    presence of dark matter and dark energy in the universe. We have also examined
    the behaviour of pressure in our model. It is negative and is dominant over
    density $\simeq – 0.7 \rho_0$.

    Submission history

    From: Gopi Kant Goswami Dr [view email]

    Wed, 26 Oct 2022 13:55:34 UTC (1,910 KB)

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