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I What does L star mean in the Schechter function?

  1. Jun 5, 2018 #1
    I'm trying to understand the Schechter function, I read on Wikipedia that the L star term in the function is the 'characteristic galaxy luminosity where the power-law form of the function cuts off'. What does this mean exactly?
     
  2. jcsd
  3. Jun 5, 2018 #2

    phyzguy

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    It's just an empirical fitting function to the brightness distributions. It's found empirically that the number of galaxies in a certain brightness range increases as a power law at the faint end, but drops off more quickly (exponentially) at the bright end. The L* luminosity is where the function transitions from one behavior to the other. These slides have a nice description.
     
  4. Jun 6, 2018 #3
    Thanks for the explanation
     
  5. Jun 6, 2018 #4
    L* is the luminosity of a giant galaxy like the Milky Way or Andromeda. Such galaxies are rare, and galaxies much brighter are even rarer.

    See this article on super spiral galaxies for more.
     
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