# Binding energy of a galaxy?

I'm a novice in physics and new to the forms, so please forgive me if this is a dumb question or if this is in the wrong section to be posted, but how would one find the gravitational binding energy of our galaxy? I know their is a formula for a uniform sphere $U= 3GM^2/5r$, however I assume for a galaxy the method would be extremely different if its even possible to give an accurate figure.

So I ask this, what would be the necessary energy needed to break the binding energy of the galaxy with a well placed rapid release of energy (explosion), I know physics would say this hypothetical event is a big no no, but what would it be if this were a possibility?

• An explosion is probably not the way to proceed if your goal is to unbind a galaxy. One could imagine calculating the escape velocity of each star in a galaxy and somehow applying an impulse to each sufficient to accomplish the escape. A more difficult issue would be how to unbind the dark matter in each galaxy. – Lewis Miller Mar 30 '16 at 0:21
• If you have reasonable estimates for the matter and dark matter densities, then you could also produce reasonable estimates for the total gravitational binding energy. The thing is... do you count dark matter as part of your galaxy? If you do, there is probably almost no way of removing it. You can remove baryonic matter using non-gravitational interaction, but that would leave a probably mostly intact dark matter galaxy behind. To remove that you would need a giant gravitational "sweeper", which may take a very long time to get the job done. – CuriousOne Mar 30 '16 at 0:52
• I see, well what if this hypothetical event was just the energy needed to liberate all of the mass (excluding dark matter) to infinity, Could this work in mathematics at least? – user112754 Mar 30 '16 at 3:16