The largest known galaxy is just 100x more massive than Milky Way. I wonder if there is some physical mechanism (some equilibrium) which limits the size of galaxies or if it is just because of limited time ( i.e. that the homogeneous mass distribution caused by inflation phase of space expansion was not able to form bigger inhomogenities by graviational instability during the time of 13.6 bilion years )
In case of stars, there is clearly a physical process which limits the size of newly formed stars: radiation energy due to fusion of hydrogen grows faster with mass of star than gravitation force. So, if a massive star core is formed it blows off the rest of the gas in the primordial nebula, so the star cannot grow anymore.
Is there some similar process in the formation of galaxies?