This shows cosmic rays (relativistic particles) which are accelerated in supernovae explosions deep within the galaxy, as they diffuse and stream out of the galaxy (propagating past the galactic outflows into the circum-galactic medium (CGM) and inter-galactic medium. This builds up a smooth, quasi-spherical “cosmic ray halo” in the CGM extending beyond the virial radius (dashed white circle, evolving in time). The cosmic ray energy density falls off relatively gently as a power-law away from the galaxy. This provides additional support for the gas in the CGM, modifying the growth of the galaxy. This is a Milky Way mass galaxy at present day (our “m12i” galaxy). Movie made by Cameron Hummels.