Ultra-faint dwarf galaxies, among the tiniest and faintest galaxies known, may hold the key to understanding one of the Universe’s biggest mysteries: the true nature of dark matter. A new study reveals that even a single collision between dark matter particles every 10 billion years — roughly the age of the Universe — is enough to explain the dark matter cores observed in these small systems. These galaxies, which contain only a few thousand stars, are dominated by dark matter and have relatively simple evolutionary histories. That makes them ideal cosmic laboratories for testing theories

A new study published in Astronomy & Astrophysics unveils a powerful way to determine the size of dark matter haloes—the massive, invisible structures that host galaxies—by simply measuring how large galaxies appear in deep astronomical images. Researchers Ignacio Trujillo and Claudio Dalla Vecchia, from the Instituto de Astrofísica de Canarias (IAC) and the Universidad de La Laguna (ULL), demonstrate that galaxy size can serve as a precise proxy for halo size, offering measurements up to six times more accurate than previous methods. Using the cutting-edge EAGLE cosmological simulations