28 research outputs found
Squared torsion gravity and its cosmological implications
We present the coupling of the torsion scalar and the trace of
energy-momentum tensor , which produces new modified
gravity. Moreover, we consider the functional form
where and are
free parameters. As an alternative to a cosmological constant, the
theory may offer a theoretical explanation of the late-time
acceleration. The recent observational data to the considered model especially
the bounds on model parameters is applied in detail. Furthermore, we analyze
the cosmological behavior of the deceleration, effective equation of state and
total equation of state parameters. However, it is seen that the deceleration
parameter depicts the transition from deceleration to acceleration and the
effective dark sector shows a quintessence-like evolution.Comment: 7 figures, 8 pages Comments are welcom
Reconstruction of Lagrangian for various cosmological scenario
The variety of theories that can account for the dark energy phenomenon
encourages current research to concentrate on a more in-depth examination of
the potential impacts of modified gravity on both local and cosmic scales. We
discuss some cosmological reconstruction in cosmology (where is
the non-metricity scalar, and is the trace of the energy-momentum tensor)
corresponding to the evolution background in
Friedmann-La\^imatre-Robertson-Walker (FLRW) universe. This helps us to
determine how any FLRW cosmology can arise from a specific theory. We
use the reconstruction technique to derive explicit forms of
Lagrangian for the different kinds of matter sources and Einstein's static
universe. We also formulate the models using several ansatz forms of the
function for . We demonstrate that several classes of
theories admit the power-law and de-Sitter solutions in some ranges of
. Additionally, we reconstruct the cosmological model for the scalar
field with a specific form of . These new models with cosmological
inspiration may impact gravitational phenomena at other cosmological scales.Comment: PLB published versio
Cosmology with viscous generalized Chaplygin gas in gravity
We use the hybrid model of bulk viscosity and generalized chaplygin gas
(GCG), named the viscous generalized chaplygin gas (VGCG) model, which is
thought to be an alternate dark fluid of the universe. We explore the dynamics
of the VGCG model in the framework of the non-metricity gravity using
the functional form , where and are arbitrary
constants. For the purpose of constraining model parameters, we use recent
observational datasets such as Observational Hubble data, Baryon Acoustic
Oscillations, and Type supernovae data. According to our study, the
evolution of the deceleration parameter and the equation of state (EoS)
parameter show a transition from deceleration to an acceleration phase and
its deviation from the CDM model.Comment: Annals of Physics published versio
Dark energy constraint on equation of state parameter in the Weyl type gravity
The equation of state parameter is a significant method for characterizing
dark energy models. We investigate the evolution of the equation of state
parameter with redshift using a Bayesian analysis of recent observational
datasets (the Cosmic Chronometer data (CC) and Pantheon samples). The
Chevallier-Polarski-Linder parametrization of the effective equation of state
parameter, , where
and are free constants, is confined to the Weyl type
gravity, where represents the non-metricity and is the trace
of the energy-momentum tensor. We observe the evolution of the deceleration
parameter , the density parameter , the pressure , and the
effective equation of state parameter . The cosmic data limit for
does not exclude the possibility of . It is seen that the
parameter shows a transition from deceleration to acceleration, as
well as a shift from to .Comment: Annals of Physics accepted versio
Interaction of divergence-free deceleration parameter in Weyl-type gravity
We study an extension of symmetric teleparallel gravity i.e. Weyl-type
gravity and the divergence-free parametrization of the deceleration
parameter ( and are
free constants) to explore the evolution of the universe. By considering the
above parametric form of , we derive the Hubble solution and further impose
it in the Friedmann equations of Weyl-type gravity. To see whether
this model can challenge the CDM limits, we computed the constraints
on the model parameters using the Bayesian analysis for the Observational
Hubble data () and the Pantheon sample (). Furthermore, the
deceleration parameter depicts the accelerating behavior of the universe with
the present value and the transition redshift (at which the
expansion transits from deceleration to acceleration) with and
confidence level. We also examine the evolution of the energy
density, pressure, and effective equation of state parameters. Finally, we
demonstrate that the divergence-free parametric form of the deceleration
parameter is consistent with the Weyl-type gravity.Comment: Chinese Journal of Physics published versio