Abstract The standard Λ Cold Dark Matter (ΛCDM) cosmological model provides a good
description of a wide range of astrophysical and cosmological data. However, there are a …

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 …

Despite the remarkable success of the Λ Cold Dark Matter (Λ CDM) cosmological model, a
growing discrepancy has emerged (currently measured at the level of∼ 4− 6 σ) between the …

We review the current status of Early Dark Energy (EDE) models proposed to resolve the
“Hubble tension”, the discrepancy between “direct” measurements of the current expansion …

The Hubble tension has now grown to a level of significance which can no longer be
ignored and calls for a solution which, despite a huge number of attempts, has so far eluded …

The dawn of the twenty-first century came with very positive prospects for gravity, cosmology,
and astrophysics. Technological progress made it possible for cosmology to enter to its …

The Λ CDM model provides a good fit to most astronomical observations but harbors large
areas of phenomenology and ignorance. With the improvements in the precision and …

New physics increasing the expansion rate just prior to recombination is among the least
unlikely solutions to the Hubble tension and would be expected to leave an important …

We constrain six possible extensions to the Λ cold dark matter (CDM) model using
measurements from the Dark Energy Survey's first three years of observations, alone and in …