[Submitted on 26 Oct 2022]
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]
[v1]
Wed, 26 Oct 2022 13:55:34 UTC (1,910 KB)
