Related papers: Future constraints on the Hu-Sawicki modified grav…
We perform a phase space analysis of a generalized modified gravity theory with nonminimally coupling between geometry and matter. We apply the dynamical system approach to this generalized model and find that in the cosmological context,…
The observed acceleration of the universe, explained through dark energy, could alternatively be explained through a modification of gravity that would also induce modifications in the evolution of cosmological perturbations. We use new…
We use observational data from Type Ia Supernovae (SNIa), Baryon Acoustic Oscillations (BAO), and Cosmic Microwave Background (CMB), along with requirements of Big Bang Nucleosynthesis (BBN), to constrain the cosmological scenarios governed…
We investigate the possibility of future singularity due to the accelerating expansion of the Universe. It has been found that the gravitational theory comprises Ricci scalar $R$ and Gauss-Bonnet invariant $\mathcal{G}$, known as…
In this paper, we present an accelerating cosmological model by constraining the free parameters using the cosmological datasets in an extended symmetric teleparallel gravity for the flat and anisotropic space-time. We employ a time…
The energy density of a scalar field $\phi$ with potential $V(\phi) \propto \phi^{-\alpha}$, $\alpha > 0$, behaves like a time-variable cosmological constant that could contribute significantly to the present energy density. Predictions of…
Since the discovery of the accelerated expansion of the Universe in 1998, modified gravity (MG) theories have attracted considerable attention as alternatives to dark energy (DE). While distinguishing the effects of MG from those of DE…
The accelerating expansion of our universe at present could be driven by an unknown energy component (Dark Energy) or a modification of general relativity (Modified Gravity). In this note we revisit the constraints on a phenomenological…
One way to account for the acceleration of the universe is to modify general relativity, rather than introducing dark energy. Typically, such modifications introduce new degrees of freedom. It is interesting to consider models with no new…
The cosmic acceleration problem remains one of the most significant challenges in cosmology. One of the proposed solutions to this problem is the modification of gravity on large scales. In this paper, we explore the well-known…
In this paper, we consider the recently proposed hybrid metric-Palatini gravitational theory, which consists of adding to the Einstein-Hilbert Lagrangian an $f(\mathcal{R})$ term constructed \`{a} la Palatini. Using the respective…
Applying the definition of the turnaround radius and the fact that the best agreement with observational data on extragalactic scales is currently provided by general relativity with the cosmological constant we consider the behaviour of…
The $f(R)$ modified gravity theory can explain the accelerating expansion of the late Universe without introducing dark energy. In this study, we predict the constraint strength on the $f(R)$ theory using the mock data generated from the…
We explore observational constraints on possible deviations from Newtonian gravity by means of large-scale clustering of galaxies. We measure the power spectrum and the bispectrum of Sloan Digital Sky Survey galaxies and compare the result…
Cosmic acceleration may be due to modifications of cosmic gravity and to test this we need robust connections between theory and observations. However, in a model independent approach like effective field theory or a broad class like…
We perform the dynamical system analysis for the homogeneous and anisotropic Bianchi I cosmology in the context of Hu-Sawicki $f(R)$ gravity with parameters $\{n,C_{1}\}=\{1,1\}$. Deriving the corresponding four-dimensional dynamical system…
Possible models of modified gravity are being extensively studied now, with most phenomenological motivations coming from puzzles and tensions in cosmology due to a natural desire to better fit the known and newly coming data. At the same…
This thesis focuses on late-time cosmic acceleration within modified theories of gravity, using various observational data sets and statistical analysis. The Universe is assumed to be spatially homogeneous and isotropic and is described by…
Recent observations of high-redshift Type Ia supernovae have placed stringent constraints on the cosmological constant $\Lambda$. We explore the implications of these SNe observations for cosmological models in which a classically evolving…
The cosmological constant and its phenomenology remain among the greatest puzzles in theoretical physics. We review how modifications of Einstein's general relativity could alleviate the different problems associated with it that result…