RE: The advent of hypothetical pion stars - a new form of compact objects in the universe
I had a quick look at the paper. I am not too sure I got an answer to my question, because I honestly understood less than half of it.
I believe what they call the pionic pressure would be what counterbalances gravity. Then, I have to extrapolate to what I know. Without entering the details, would it be that the compression by gravity of the pions force-stacks each of them into a state resulting in a counter pressure, analogously to the state degeneracy of electrons or neutrons that stabilizes white dwarfs and neutron stars respectively?
In the end, there is no need for a source of energy. Quantum physics rules do the job.
In terms of gut feelings (i.e. with no logic), I am quite doubtful of the past or present existence of these pion-electron stars, and that even if I love exotic things ;-)
In short, the weak isospin interactions of the pions balance the gravitational collapse. It is sufficient and you don't need to invoke anything new. (On top of that, they have verified that the pion condensate is stable, as pion are unstable particles.)