"I'm left to guess that astronomers are allowing for this and still can't account for the behavior." That's correct. Black holes have been inferred at the centers of several galaxies from star motions near the centers. The hitch is that stars' galactic orbital velocities don't generally seem to drop off with distance from the center as fast as one might expect.
There's a great website on the Milky Way's black hole at Black Hole Slide Show. The slide show includs an actual movie of stars, not an animation, of stars in motion around the black hole. (You can download the movie from Black Hole Movie.)
Won't claim to understand it all, but that's one heck of a slide show and movie. Thanks!
My memory fails me, I have a distinct memory of reading an artice not to long ago, Thought it was NYTimes but did a search without results. The thesis was something to the effect that the expanding universe was steadily decreasing the overall electrical potential of the universe. This was having the effect of changing the interior distance of electron shells in all matter. The result, it was claimed, would skew the spectra we were observing and alter the frequencies in a way that is now explained solely by redshift. Presumably an electron falling down a shell -releasing a photon of fixed frequency-would issue a photon of uniformly shifted frequency if all those shells were altered on a macro level.
I won't even go so far as to say "it's just crazy enough to be true" but just want to know if anyone else recalls the article. (If not I solemnly swear I will never read another Science Fiction novel based on Velikovsky's work again)
Seems to me though that if it is true it might partly explain galaxies spinning too slowly, (since we measure their rotation by redshift)