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Black holes: Some astronomers detected flashes of x-ray in the cosmos

  1. Dec 9, 2012 #1
    Some astronomers detected flashes of x-ray in the cosmos. They say it can only be possible because matters temperature increases to million degrees to radiate into x-rays, and only objects entering into black hole could radiate x-rays in whole cosmos.
    How can you detected x-ray radiation from lump of material disappearing into black hole? I mean how can even radiation can escape from such strong gravity of black hole, even light(radiation) can't escape from it? Or is it the radiation would form from the matters out of the event horizon of the black hole? Can radiation still be formed out of the event horizon too?
    Last edited: Dec 9, 2012
  2. jcsd
  3. Dec 9, 2012 #2


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    Re: Black holes

    Yes, the radiation is emitted before the in falling object crosses the event horizon. Try searching for "black hole accretion disk" to get a sense of just how intense and violent conditions can be even outside the horizon.

    (in fact, for an object falling into a black hole, the event horizon itself passes with no great drama. The intense tidal forces you read about are first encountered outside the horizon)
  4. Dec 10, 2012 #3


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  5. Dec 10, 2012 #4


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    Re: Black holes

    That's not quite right. It IS right for small black holes but for super-massive black holes tidal forces don't get intense until you are well inside the EH.
  6. Dec 25, 2012 #5
    Re: Black holes


    The law of conservation of angular momentum states:

    L=total spin+total orbit.

    Due to this angular momentum gases falling inside the black hole, which has a very big mass will create a disc type form. In case of such compact object, the heat radiated is huge, causing huge amount of radiation, X-rays which can be detected by telescopes.
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