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 …

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 …

We report observations from the Hubble Space Telescope (HST) of Cepheid variables in the
host galaxies of 42 Type Ia supernovae (SNe Ia) used to calibrate the Hubble constant (H 0) …

The cosmological principle (CP)—the notion that the Universe is spatially isotropic and
homogeneous on large scales—underlies a century of progress in cosmology. It is …

Abstract The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders
about the fundamental theory of nature at play in the extreme gravity regime, where the …

▪ The Hubble parameter, H 0, is not an univocally defined quantity: It relates redshifts to
distances in the near Universe, but it is also a key parameter of the ΛCDM standard …

Measurement of the distances to nearby galaxies has improved rapidly in recent decades.
The ever-present challenge is to reduce systematic effects, especially as greater distances …

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 …

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 …