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TOPIC: Supermassive Black Holes


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RE: Supermassive Black Holes
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The May issue of Astronomy magazine points out that nobody knows why it's true, but scientists have discovered that in our neck of the universe the mass of a galaxy's central supermassive black hole is 0.14 percent of the mass of the entire galaxy, if it's an elliptical galaxy. The same ratio, 0.14 percent, holds true for the mass of the black hole compared with the central bulge of a spiral galaxy. The magazine cites an astronomer named Dominik Riechers of the California Institute of Technology, Pasadena, for the calculations.
In many galaxies, including our Milky Way, the black hole is quiet, hardly ever devouring stars. At least for now, few stars wander close enough for it to snag. But in other galaxies, holes are consuming an enormous amount of material.

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Mystery Space Object May Be Ejected Black Hole

A mystery object in a galaxy  far, far away could be a supermassive black hole that got booted from its home galaxy's centre, according to a new study.
Then again, the strange body could be a rare type of supernova or an oddball "midsize" black hole - more massive than black holes born when single stars explode but "lighter" than the supermassive ones at the centres of galaxies.

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Warped stars feed black holes to fatten them up

Why are supermassive black holes so, well, supermassive? It has long been a mystery how enough matter can reach these cosmic gluttons to swell them to such large sizes. Now it seems the answer could be connected to a starry disc at the heart of the Andromeda galaxy. Although they may be hard to see, such discs may be common.
Black holes millions or billions times as massive as the sun reside at the heart of most galaxies, including our own. These black holes have been fattened up by huge amounts of gas. But astronomers don't know how that gas makes it through a final hurdle, migrating the last dozens or hundreds of light years to be eaten.

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