It has been suggested that some if not most elliptical galaxies are the result of two similarly sized spiral galaxies colliding: <a href="http:&#x2F;&#x2F;spacetelescope.org&#x2F;images&#x2F;potw1148a&#x2F;" rel="nofollow">http:&#x2F;&#x2F;spacetelescope.org&#x2F;images&#x2F;potw1148a&#x2F;</a><p>The most energetic event I can think of would be two galactic core sized black holes colliding. Has this been ruled out already as a possible cause of FRBs?