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 …

Multiply imaged time-variable sources can be used to measure absolute distances as a
function of redshifts and thus determine cosmological parameters, chiefly the Hubble …

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 …

The recent Hubble constant, H 0, tension is observed between the value of H 0 from the
cosmic microwave background (CMB) and Type Ia supernovae (SNe Ia). It is a decade since …

The distribution of the non-luminous matter in galaxies of different luminosity and Hubble
type is much more than a proof of the existence of dark particles governing the structures of …

The Λ CDM cosmology passes demanding tests that establish it as a good approximation to
reality. The theory is incomplete, of course, and open issues are being examined in active …

We study the link between baryons and dark matter (DM) in 240 galaxies with spatially
resolved kinematic data. Our sample spans 9 dex in stellar mass and includes all …

Modeling galaxy formation in a cosmological context presents one of the greatest
challenges in astrophysics today due to the vast range of scales and numerous physical …

Observations of galaxy isophotes, long-slit kinematics, and high-resolution photometry
suggested a possible dichotomy between two distinct classes of elliptical galaxies. But these …

Cosmicflows-2 is a compilation of distances and peculiar velocities for over 8000 galaxies.
Numerically the largest contributions come from the luminosity–line width correlation for …