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HLX-1 brightest ultra-luminous X-ray source known.

  1. Sep 9, 2010 #1
    The most extreme ultra-luminous X-ray source, HLX-1 is 300light years from Earth. HLX-1 is the brightest ultra-luminous X-ray source known. Also it is not a supermassive black hole but it is the center of the galaxy. How can it be the brightest x-ray source and be a small black hole?
  2. jcsd
  3. Sep 9, 2010 #2


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    Luminosity falls off as the square of the distance from the emitter and the observer. Close enough, and any strong X-ray source (no matter how small) could be the "brightest".
  4. Sep 9, 2010 #3


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    Note that it is not 300 light years away, but 300 MILLION light years away. Slightly further.
  5. Sep 9, 2010 #4

    D H

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    HLX-1 is in the galaxy ESO 243-49, about 300 million light years from the Earth. It is not at the center of a galaxy; that is one of the hallmarks of an ultraluminous X-ray source. The other hallmark is that they are ultraluminous, which means that their X-ray output exceeds that which would result from a stellar black hole.

    In other words, ultraluminous X-ray sources are neither stellar-mass black holes nor active galactic nuclei. They are something in between, such as an intermediate mass black hole.
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