This is a nice article on magnetic fields in galaxies. http://www.scholarpedia.org/article/Galactic_magnetic_fields
The black hole at the center of the galaxy is not the main source of the magnetic field even if black holes can have charges and magnetic fields. The reason you have magnetic fields in stars and other structured objects like galaxies is that in confined situations like inside the core of a star you can have a very ionized plasma that moves very fast and these are the conditions to create strong magnetic fields. In free cold interstellar space is more difficult to create electrical and magnetic fields and currents. The role of electrical and magnetic fields is recognized by modern astrophysics; the issue here is if they are equally or even more important than gravity in determining the dynamic and evolution of astronomical objects and the universe as a whole. It is an idea that has been explored and it was found not to be the case. There is a book called the Big Bang Never happened: http://www.amazon.com/Big-Bang-Never-Happened-Refutation/dp/067974049X that is a popularization of Alfven ideas. It is an interesting read and one can learn a lot from it but these ideas are proven not to be adequate to explain all the observational facts that the Big Bang theory can explain. We have accumulated a lot of information with detailed maps of the Cosmic Background and the classical Big Bang Theory plus inflation is the best cosmological model we have. For what regards star and planetary formation electrical and magnetic fields play a role but again is not dominant but a secondary effect. Giovanni On Sun, Jan 20, 2013 at 2:28 PM, <mix...@bigpond.com> wrote: > In reply to Giovanni Santostasi's message of Sun, 20 Jan 2013 14:07:00 > -0600: > Hi, > [snip] > >Proponents of plasma cosmology claim electrodynamics is as important as > gravity in explaining the structure of the universe, and speculate that it > provides an alternative explanation for the evolution of galaxies[8] and > the initial collapse of interstellar clouds.[19] In particular plasma > cosmology is claimed to provide an alternative explanation for the flat > rotation curves of spiral galaxies and to do away with the need for dark > matter in galaxies and with the need for supermassive black holes in galaxy > centres to power quasars and active galactic nuclei.[8][37] This is > controversial, as theoretical analysis shows that "many scenarios for the > generation of seed magnetic fields, which rely on the survival and > sustainability of currents at early times [of the universe are > disfavored]",[20] i.e. Birkeland currents of the magnitude needed (say 1018 > Amps) for galaxy formation are thought to not exist.[16] > > Two questions: > > 1) Can the massive black holes at the core of galaxies have magnetic > fields? > 2) All stars stream plasma into space continually, much of which simply > cools > down and becomes cold interstellar plasma (as well as gas). Wouldn't you > expect > electrical and magnetic fields to develop in this cold plasma, much as > they do > in the hot plasma of the stars? What I am trying to get at here is that > cold > plasma is largely invisible, hence there may be larger currents and fields > than > we are aware of. > > Regards, > > Robin van Spaandonk > > http://rvanspaa.freehostia.com/project.html > >
