No. There is no evidence to suggest that any galaxy has an abnormally strong electromagnetic field. Black holes are a consequence of gravitational collapse, not electromagnetism. They usually form when a star above a certain mass collapses.
Yes. Some galaxies, particularly irregular galaxies, appear to lack supermassive black holes.
Not all galaxies, but it is believed that the majority of galaxies have central black holes.
Yes they do.
Active Galaxies are thought to be powered by rotation
It's not "galaxy stars", but galaxies, that have the black holes at their center.All, or most, galaxies have a giant black hole at their center.
Yes
Let's put it this way... All larger galaxies have huge black holes in their center. In addition to that, you can expect any galaxy to have a significant number of stellar black holes.
It's generally believed that galaxies first formed around "ordinary" black holes and over time, they grew into super massive black holes as stars were slowly "consumed" by the black hole.
in the middle of giant galaxies
All galaxies have black holes, even the Milky Way.
Pick anyone and there will be black hole in it.
Most or all galaxies appear to have supermassive black holes at their centers and probably have stellar mass black holes scattered throughout.