by Chris Peterson » Sun Mar 07, 2010 8:18 pm
mark swain wrote:How did these black holes, devour their galaxies in 10 billion years?
They didn't. OJ 287 is an active galaxy. It isn't an object that has been reduced to a pair of supermassive black holes orbiting each other. It is not that difficult to explain as the simple merger of a pair of galaxies, each with its own supermassive black hole. The contents of the two galaxies haven't gone anywhere, but still exist as the contents of the merged pair. This newer galaxy simply has a pair of supermassive black holes at its center, instead of the usual one.
18 billion solar masses. + 100 million solar mass = How many galaxies? How long does it take to merge 10 galaxies? But even so, Mr Chris P said him self, Black holes do not feed very fast. A finite time for black hole growth?
Black holes don't feed fast. But the mechanism by which the supermassive black holes found at the center of most galaxies initially formed is not yet well understood. It did not necessarily involve their growth by accretion as we now see it. These black holes may have formed quite quickly by different processes altogether. This includes the most massive cases, as well. 18 billion solar masses is still much less than the mass of many galaxies. I see no reason to assume that very massive black holes necessarily formed from multiple galactic mergers, or that they required an extraordinary amount of time to form. There are reasonable theories that explain their existence, even if those theories need more work.
[quote="mark swain"]How did these black holes, devour their galaxies in 10 billion years?[/quote]
They didn't. OJ 287 is an active galaxy. It isn't an object that has been reduced to a pair of supermassive black holes orbiting each other. It is not that difficult to explain as the simple merger of a pair of galaxies, each with its own supermassive black hole. The contents of the two galaxies haven't gone anywhere, but still exist as the contents of the merged pair. This newer galaxy simply has a pair of supermassive black holes at its center, instead of the usual one.
[quote]18 billion solar masses. + 100 million solar mass = How many galaxies? How long does it take to merge 10 galaxies? But even so, Mr Chris P said him self, Black holes do not feed very fast. A finite time for black hole growth?[/quote]
Black holes don't feed fast. But the mechanism by which the supermassive black holes found at the center of most galaxies initially formed is not yet well understood. It did not necessarily involve their growth by accretion as we now see it. These black holes may have formed quite quickly by different processes altogether. This includes the most massive cases, as well. 18 billion solar masses is still much less than the mass of many galaxies. I see no reason to assume that very massive black holes necessarily formed from multiple galactic mergers, or that they required an extraordinary amount of time to form. There are reasonable theories that explain their existence, even if those theories need more work.