with one... riyanatarajan: continuing from earlier....we cannot tell the difference once the matter is accreted what is was composed of. So yes indeed a small portion of the mass of the black holes that we detect in the centers of galaxies could be dark matter! Jason (moderator): Do you have a question you've been waiting to ask? Go for it! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions. Bekamancer: Is there a large difference between galaxies that have a black hole at the center, and those that do not? Ezequiel: at least in the "local" Universe, we found that all massive galaxies also have massive black holes, while very small galaxies do not have central black holes at all. Chateau: Do you have a favorite black hole? riyanatarajan: Yes, its the one in the center of the galaxy M87. Its one of the most massive nearby black holes and produces an impressive jet that is visible nicely in radio waves. natasha_qurban: what happen when some object will exceed the speed of light Kevin: The theory of relativity tells us that unfortunately nothing can move faster than the speed of light... Thomaspoke: For how long do you think the black holes have been growing? Ezequiel: which ones? We know that after a galaxy merger, black holes can grow very rapidly for