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super massive black hole
is it true that every galaxy has one?
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wrote in message
om... is it true that every galaxy has one? It does not appear to be so. |
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wrote in message
om... is it true that every galaxy has one? It does not appear to be so. |
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"Llanzlan Klazmon The 15th" wrote in message 7.6... ) wrote in om: is it true that every galaxy has one? Certainly appears to be a common feature of medium to large size galaxies. Not sure about the dwarf galaxies. L. Don't know either. But evidence suggests some globular clusters may contain black holes. Dave |
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"Llanzlan Klazmon The 15th" wrote in message 7.6... ) wrote in om: is it true that every galaxy has one? Certainly appears to be a common feature of medium to large size galaxies. Not sure about the dwarf galaxies. L. Don't know either. But evidence suggests some globular clusters may contain black holes. Dave |
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On Fri, 07 Nov 2003 13:48:26 +0000, Dave wrote:
"Llanzlan Klazmon The 15th" wrote in message 7.6... ) wrote in om: is it true that every galaxy has one? Not quite. In our local group of galaxies M33 does not have one. See: Merritt D, et al, No Supermassive Black Hole in M33, Science 2001; 293: 1116-18 Certainly appears to be a common feature of medium to large size galaxies. Not sure about the dwarf galaxies. Some dwarf galaxies have, M32 for example. See: van der Marel R P, et al, A massive black hole at the centre of the quiescent galaxy M32, Nature 1997; 385: 610-12 Don't know either. But evidence suggests some globular clusters may contain black holes. Some Globulars may be remnant of the core of cannibalised dwarf galaxies. Thus some of them should have a black hole. But they are thought to be of medium size - corresponding to their total mass, i.e., 0.2% of the total mass of the core. See: NASA Press Release 02-174, 17 September 2002 -- Gautam Majumdar Please send e-mails to |
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Some of the books I read have blackholes were formed before stars(right
out of the big bang) Never read of any blackhole"s decaying. If I was told there are blackholes with the mass of 300 million suns I would not be amazed. I would add this thought. If it was spinning close to light speed it would be natures most unmovible object(like a gyro) Bert |
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"G=EMC^2 Glazier" wrote in message ... Some of the books I read have blackholes were formed before stars(right out of the big bang) Never read of any blackhole"s decaying. If I was told there are blackholes with the mass of 300 million suns I would not be amazed. I would add this thought. If it was spinning close to light speed it would be natures most unmovible object(like a gyro) Bert Hawking says that small BHs do tend to 'decay'. Near the event horizon virtual, antiparticle/particle pairs are produced, of which one goes into the BH. Hawking realised that the smaller the BH, the greater the likelihood that one half of a pair would be absorbed (it's all to do with the curvature of spacetime near to the event horizon of large & small BH's). However, whether a particle or an anti-particle was absorbed, Hawking seems to have shown that there has been an energy loss inside the BH - hence its mass decreased. Since this occurs slowly for medium size BBs, and faster for smaller BBs, it seems to be that BBs will gain virtual mass (i.e. lose real mass) as time goes by, and the rate of mass loss will increase with time; ending with a burst of gamma radiation (or something) Hawking's analysis showed that if planet sized BHs had been created at the BB stage, then they would be bursting into nearby gamma ray explosions just about now. However, AFAIK there's NO evidence that there are any nearby local BHs evaporating into bursts of gamma radiation. |
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