| What is at the center of galaxies, can be interpreted from more than one paradigm. Currently the professional and academic communities work within the gravitationally centered paradigm of black holes and dark matter.
Along side this paradigm there are others, for instance the more electromagnetically centered paradigm of plasma cosmology, where gravity still plays a role but EM is also taken into account. In the EM view, dark matter turns into the previously ignored EM forces, and the evidence for black holes can be viewed as evidence for plasma and EM dominated effects, such as large scale double-layers, current sheets, Birkeland and other type currents. "Hot gas" is really a plasma, and the dynamic nature of EM forces and plasmas are considered across all the scales.
The center of the galaxy can be considered part of a large EM generator/source in a sense. On the intergalactic scale, galaxies are connected through fields and currents to a very large scale network of energy and matter transferring and storage mechanisms. These filaments and current sheets create a build up of structure and separation of regions in space, resulting in a somewhat cellular and filamentary structure of matter on the very large scale.
Within the individual galactic scale, stars can be considered sinks, or drains somewhat like a light bulb in a circuit, of the energy produced and/or gathered/stored within each galaxy. | 