Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Schechter Function of Galaxy Luminosity-Density relationship

  1. Feb 2, 2006 #1
    Hello. I'm plowing through Linda Sparke's "Galaxies in the Universe: An Introduction". I'm enjoying it quite well and learning a lot. But then I get to Equation 1.18 in the book and am a little confused because it uses variables not previously introduced.

    Not sure if I can do it here but the equation introduces a quantity n-star, but doesn't define how it gets in there or what it is. The text gives n-star's value as .019h^3 per Megaparsec. h is the expansion rate of the universe. Is this the number of stars per Megaparsec? And of course correcting for the expansion of the Universe.

    I'm sure I'll have quite a few more questons as I go along with this book. Wish I had the time to take some real courses in this. Oh well.

    All feedback appreciated.


  2. jcsd
  3. Feb 3, 2006 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The precise definition can be found here:

    http://scienceworld.wolfram.com/astronomy/SchechtersLuminosityFunction.html" [Broken]

    You can think of it roughly as being the number density of L* galaxies, which are Milky Way-sized galaxies.
    Last edited by a moderator: May 2, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook