In this talk I will outline a fast and accurate approach to introduce modified gravity (MG) consistently in Cosmological N-Body simulations, using the COLA (COmoving Lagrangian Acceleration) method, a fast and approximate method to generate non-linear realizations of the density field. The matter power spectrum computed from these simulations is shown to be in agreement with known results in...
General Theory of Relativity needs at least one modification - the Cosmological Constant. Yet there are possibilities for other modified theories of gravity to explain the accelerated expansion. In this talk I'm going to discuss the impact of Modified Gravity on the two-body problem. In particular, with the latest observational constraints from the galactic center, binary pulsars and the Milky...
General relativity (GR) exists in different formulations. They are equivalent in pure gravity but generically lead to distinct predictions once matter is included. After a brief overview of various versions of GR, we focus on metric-affine gravity, which avoids any assumption about the vanishing of curvature, torsion, or nonmetricity. We use it to construct an action of a scalar field coupled...
We check quantum stability of the generalized Proca theories in curved spacetime by computing the quantum gravitational corrections using Vilkovisky- Dewitt formalism. First we consider a range of the coupling constants to maximize the predictability of EFT. We find that there exists a regime where classical nonlinearity dominates while quantum corrections are still suppressed protecting EFT...
Holographic dark energy with the Hubble radius as infrared cutoff is considered as a candidate to explain the late-time cosmic acceleration for 20 years and it can solve the coincidence problem. However, a nonzero equation of state is only possible if there is an interaction between dark energy and cold dark matter. In this talk I show that the resulting matter power spectrum and cosmic...
I will present a new cosmological model in which the expansion is no longer affected by spatial curvature (i.e. Ω = 1, ∀ Ω_k), while the measure of distances still requires this curvature. The model originates from a modification of Einstein's equation in a which a term related to the topology of the Universe is added. First, I will present the main motivation for this modification, which is...
We investigate the backreaction of nonlinear perturbations on the global evolution of the Universe within the cosmic screening approach. To this end, we have considered the second-order scalar perturbations. An analytical study of these perturbations followed by a numerical evaluation shows that, first, the corresponding average values have a negligible backreaction effect on the Friedmann...
To recreate the cosmological models, we employed the parametrization approach in modified teleparallel Gauss-Bonnet gravity. It has been interesting to apply the parametrization approach to investigate cosmological models. The real benefit of using this method is that the observational data may be incorporated to examine the cosmological models. Several cosmological parameters were examined,...
