abstract:The gravitational binding energy of an object consisting of loose material, held together by gravity alone, is the amount of energy required to pull all of the material apart, to infinity. It is also the amount of energy that is liberated (usually in the form of heat) during the accretion of such an object from material falling from infinity.
Many oftheseappear tobefairlyuniform, so by the virial theorem the totalkineticenergyshould behalf the totalgravitational binding energyof the galaxies.