We study cosmological observables on the past light-cone of a fixed observer in the context
of clustering dark energy. We focus on observables that probe the gravitational field directly …

We consider the screening of the axio-dilaton fields when both the dilaton and the axion
couple to matter with Yukawa couplings. We analyze the screening of the dilaton in the …

ABSTRACT The integrated Sachs–Wolfe (ISW) effect is caused by the decay of
cosmological gravitational potential and is therefore a unique probe of dark energy …

The observed discrepancy of the Hubble parameter measurements in the local universe with
the cosmic microwave background (CMB) data may indicate a new physics. It is vital to test …

Several modified cosmological models exist, which also try to address the tensions between
data and predictions of the Λ-CDM model. Galileon models are particular scalar tensor …

The standard model of cosmology with nearly Gaussian, isotropic, scale invariant and
adiabatic initial conditions describes the cosmological observations well. However, the study …

We examine linear perturbation theory to evaluate the contribution of viscosity coefficient in
the growing of dark matter perturbations in the context of the bulk viscous dark energy model …

Aims: In this work, we address the issue of peculiar velocity measurement in a perturbed
Friedmann universe using the deviations from measured luminosity distances of standard …

In the present paper, we study the capability of interacting dark energy model with pure
momentum transfer in the dark sector to reconcile tensions between low redshift …

In this thesis we mainly focus on characterizing the non-linear evolution of dark energy and
modified gravity models with the aim to probe some of these models precisely while treating …