What can create a soliton that can fit inside a galaxy, a volume of space that is filled with excited hydrogen and helium radiating in the XUV band, a volume that produce energetic x-rays at 3.5 MeV. A low temperature BEC of atoms does not fit this profile.
The particle must be a boson that by its very nature is highly interactive and connective quantum mechanically. It also must be very light or even without mass to sustain entangled and coherent gas at high energy levels. But can produce a huge force that can counteract the force of gravity generated by the combined mass of the galaxy and strong enough to drive the soliton in a highly constrained necklace orbit that is coordinated with other galaxies.
