Galaxy Merger 2D: Dynamical Friction Sinking

Most galaxy mergers don't happen in one fast head-on smash — a small satellite galaxy orbits for millions to billions of years while Chandrasekhar dynamical friction quietly bleeds off its orbital energy and angular momentum, until it finally spirals into the host's core. This 2D top-down simulator integrates the real drag law for an isothermal-sphere halo, F_df = -4πG²M_sat²ρ(r)lnΛ/v³, alongside the host's own gravity, so you can watch the orbit decay in real time, drag to pan and scroll to zoom the orbital plane, and read the live decay chart against the analytic sinking-time prediction t_df ≈ (1.17/lnΛ)·(r_i²v_c)/(GM_sat) — the same physics governing the Milky Way's ongoing absorption of the Sagittarius and Magellanic dwarf galaxies.