Abstract Euclid is a European Space Agency medium-class mission selected for launch in
2019 within the Cosmic Vision 2015–2025 program. The main goal of Euclid is to …

Mounting observational data confirm that about 73% of the energy density consists of dark
energy which is responsible for the current accelerated expansion of the Universe. We …

Dark energy, the mysterious cause of the accelerating expansion of the universe, is one of
the most important fields of research in astrophysics and cosmology today. Introducing the …

Galaxy counts and recent measurements of the luminosity density in the near-infrared have
indicated the possibility that the local universe may be under-dense on scales of several …

Recently, there have been suggestions that the apparent accelerated expansion of the
universe is not caused by repulsive gravitation due to dark energy, but is rather a result of …

I discuss the spherically symmetric but inhomogeneous Lemaitre–Tolman–Bondi (LTB)
metric, which provides an exact toy model for an inhomogeneous universe. Since we …

Recently, inhomogeneous generalizations of the Friedmann–Lemaître–Robertson–Walker
(FLRW) cosmological models have gained interest in the astrophysical community and are …

We present the time drift of the cosmological redshift in a general spherically symmetric
spacetime. We demonstrate that its observation would allow us to test the Copernican …

Assuming the universe is spatially homogeneous on the largest scales lays the foundation
for almost all cosmology. This idea is based on the Copernican Principle, that we are not at a …

The apparent accelerating expansion of the universe is forcing us to examine the
foundational aspects of the standard model of cosmology—in particular, the fact that dark …