Galaxies and their dark-matter haloes have posed several challenges to the dark energy
plus cold dark matter (Λ CDM) cosmological model. These discrepancies between …

Astronomical observations reveal a major deficiency in our understanding of physics—the
detectable mass is insufficient to explain the observed motions in a huge variety of systems …

The ultra-diffuse galaxies DF2 and DF4 in the NGC 1052 group share several unusual
properties: they both have large sizes, rich populations of overluminous and large globular …

We present new H i interferometric observations of the gas-rich ultra-diffuse galaxy AGC
114905, which previous work, based on low-resolution data, identified as an outlier of the …

We present new spectroscopic observations of the diffuse Milky Way satellite galaxies Antlia
2 and Crater 2, taken as part of the Southern Stellar Stream Spectroscopic Survey (S 5). The …

We study the gas kinematics traced by the 21 cm emission of a sample of six H i-rich low
surface brightness galaxies classified as ultra-diffuse galaxies (UDGs). Using the 3D …

The standard cold dark matter plus cosmological constant model predicts that galaxies form
within dark-matter haloes, and that low-mass galaxies are more dark-matter dominated than …

We use the IllustrisTNG cosmological hydrodynamical simulation to study the formation of
ultradiffuse galaxies (UDGs) in galaxy clusters. We supplement the simulations with a …

We present spatially resolved stellar kinematics of the well-studied ultra-diffuse galaxy
(UDG) Dragonfly 44, as determined from 25.3 hr of observations with the Keck Cosmic Web …

We study the formation of ultradiffuse galaxies (UDGs) using the cosmological
hydrodynamical simulation TNG50 of the Illustris-TNG suite. We define UDGs as dwarf …