Dark subhaloes may steer tiny galaxies toward a universal fate

A new study argues that dwarf spheroidal galaxies are guided toward a universal 'dynamical attractor' by chaotic heating from dark subhaloes and by tidal stripping from larger galaxies, meaning their varied present-day shapes are largely an evolutionary outcome rather than initial conditions. Using extensive N-body simulations, the researchers found these dwarfs shed most of their dark matter before losing stars, and real dwarfs show a consistent dynamical track with stellar velocity dispersion about half the maximum dark-matter velocity, a result that holds across cuspy and cored dark matter profiles. Isolated dwarfs would take up to the age of the universe to reach this attractor.