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Radio Waves emitted by Black Holes

  1. May 2, 2006 #1
    I was reading up on black holes when i thought of this. Black holes have been found to emit radio waves. I was wondering if this was actually light that managed to escape the black hole. Here is my thinking on this.
    From what i know light travels in a straight line through points through space. A BH distorts space time which causes light to travel straight on the path into the BH. If light is expelled at 90 degree angle to the surface of the BH it should travel at lightspeed away from the BH. I was thinking then that the light wave's wavelength would be stretched into becoming a radio wave. If this is true we should be able to "read" the output. Comments?
  2. jcsd
  3. May 2, 2006 #2


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    All radiation related to a black hole (except for infinitesimal amount called Hawking radiation) comes from charged particles (outside) falling into the black hole and radiating as they accelerate into the hole.
  4. May 2, 2006 #3


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    In radio-loud quasars, the majority of the radio emission comes from a pair of jets being expelled from the black hole and most of it originates from well away from the central engine. The mechanism of emission is synchrotron (relativistic charged particles interacting with magnetic fields). Radio-quiet quasars do have some radio emission, but I believe it's somewhat uncertain as to the source. Other than synchrotron, you can get large radio fluxes from free-free scattering (bremsstrahlung).
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