Only a handful of observations truly constrain the nature of dark matter, which is why dozens of different physical models are still viable. Several of the most popular alternatives predict that dark matter halos slowly “thermalize” over time, gradually changing shape and expanding until they form a central region of nearly constant density -- a core. This transformation would not occur if the dark matter particles were completely collision-less, as assumed in the standard model. Therefore, the presence or absence of such a core provides a powerful way to distinguish between the standard

Observations made with the James Webb Space Telescope (JWST) have revealed a larger-than-expected number of massive galaxies when the Universe was still young. The focus of this study is precisely one of these galaxies, ZF-UDS-7329. It is a very compact object, and its spectrum suggests that it formed at a very early stage, when the Universe was around 2 billion years old. According to theoretical predictions, these objects first formed a generation of stars at the center of their dark matter halos and subsequently grew by merging with other halos. However, due to the random nature of these

Ultra-diffuse galaxies, an extreme type of dwarf galaxy, have been the focus of extensive observational and theoretical studies over the past decade. With stellar masses comparable to dwarf galaxies (between 10 7 and 10 9 solar masses) but much larger in size (as defined by their effective radius), they exhibit an extremely low surface brightness. These galaxies display highly diverse properties: some have large dark matter halos, others lack them, and their number of globular clusters varies widely. Studies of their kinematics and stellar populations have shown that these extreme galaxies