GoKawiilThree dark-matter-deficient galaxies traced to ancient cosmic collision
Astronomers studying three faint galaxies—DF2, DF4, and DF9, located about 65 million light-years away—found they contain almost no dark matter, unlike most galaxies. A paper published in The Astrophysical Journal in June 2026 proposes these galaxies formed when two ordinary galaxies collided, with their gas and dust clumping together while dark matter passed through largely undisturbed, leaving behind dark-matter-poor remnants.