Black Holes and Galactic Centers . ... HST , NASA Explanation: Do all galaxies have black holes at their centers? Although not even a single galaxy has yet been proven to have a central black hole , the list of candidates has increased yet again. ... In all the galaxies studied, star speeds continue to increase closer the very center . ... This mass when combined with the limiting size make the case for the central black holes . ... NASA Web Site Statements, Warnings, and Disclaimers . ...