There is much more mass in the center of a galaxy than just the central black hole though. There are other black holes and a vast majority of the stellar mass. And its not just the very center that would need to be considered right? Its the huge discrepancy between the amount of matter near the...
Is it possible that the very high concentration of mass at the centers of galaxies is causing a significant enough time dilation to explain a non-negligible part of the rotational curve problem? i.e. time is traveling more slowly in the super-massive, black hole rich cores of galaxies and faster...