The energy source needed to create and maintain the galactic let in galaxy PKS 0521-36 is generated deep within the core of the galaxy, and is far too small to resolved. The favored mechanism behind these cosmic fireworks is a spinning, massive black hole. The hole is fueled by a continual in-fall of nearby gas and stars. This gravitational accretion process is far more efficient at converting mass to energy than thermonuclear fusion processes which power individual stars. The extraordinary high pressure and temperature generated near the hole would cause some of the in-falling gas to be ejected along the direction of the black hole's spinning axis to create the galactic let.
Dana Berry (STScI)