A number of challenges to the standard Λ CDM model have been emerging during the past
few years as the accuracy of cosmological observations improves. In this review we discuss …

The simplest ΛCDM model provides a good fit to a large span of cosmological data but
harbors large areas of phenomenology and ignorance. With the improvement of the number …

Singularities in any physical theory are either remarkable indicators of the unknown
underlying fundamental theory, or indicate a change in the description of the physical reality …

Abstract Models where dark matter and dark energy interact with each other have been
proposed to solve the coincidence problem. We review the motivations underlying the need …

The recent determination of the local value of the Hubble constant by Riess et al., 2016
(hereafter R16) is now 3.3 sigma higher than the value derived from the most recent CMB …

In this work we shall investigate the occurrence of future cosmological finite-time
singularities in the dynamical system corresponding to two cosmological theories, namely …

We wish to investigate whether there is an extension to the base ΛCDM cosmology that can
resolve the tension between the Planck observation of the cosmic microwave background …

We investigate various scenarios which include interaction forms between dark matter and
dark energy that exhibit sign reverse, namely where the transfer of energy between the dark …

The emergence of an increasingly strong tension between the Hubble rate inferred from
early-and late-time observations has reinvigorated interest in nonstandard scenarios, with …

We explore the effects of considering various infrared (IR) cutoffs, including the particle
horizon, the Ricci horizon and the Granda–Oliveros (GO) cutoffs, on the properties of Tsallis …