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Spectral index

  1. Apr 27, 2008 #1
    Hi,

    Can anybody please explain to me (in everyday language) what spectral index is? The wikipedia entry doesn't shed much light, and a lot of the textbooks give very convoluted explanations for its derivation.

    Thanks.
     
  2. jcsd
  3. Apr 28, 2008 #2
    In radio terms (in my experience), spectral index applies to synchrotron sources which have brightness, S, which changes with for different frequencies, [tex]\nu[/tex], such that [tex]S \propto \nu^{\alpha}[/tex]. For a negative [tex]\alpha[/tex] this means that when a synchrotron source is observed at higher frequencies, it will be fainter. The opposite is true for positive [tex]\alpha[/tex].
     
    Last edited: Apr 28, 2008
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