Schechter Function of Galaxy Luminosity-Density relationship

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SUMMARY

The discussion focuses on the Schechter Function related to the galaxy luminosity-density relationship, specifically addressing Equation 1.18 from Linda Sparke's "Galaxies in the Universe: An Introduction." The variable n-star, defined as 0.019h³ per Megaparsec, represents the number density of L* galaxies, which are comparable in size to the Milky Way. The conversation highlights the importance of understanding this equation in the context of cosmic expansion, as h denotes the universe's expansion rate.

PREREQUISITES
  • Understanding of the Schechter Function in astrophysics
  • Familiarity with cosmological parameters, particularly the expansion rate (h)
  • Basic knowledge of galaxy classifications, specifically L* galaxies
  • Ability to interpret equations in astrophysical literature
NEXT STEPS
  • Research the implications of the Schechter Function on galaxy formation
  • Study the role of cosmic expansion in galaxy density calculations
  • Explore the characteristics of L* galaxies and their significance in cosmology
  • Learn about the derivation and applications of the Schechter Function in observational astronomy
USEFUL FOR

Astronomy students, astrophysicists, and researchers interested in galaxy formation and the cosmic structure of the universe will benefit from this discussion.

sderamus
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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.

TIA

Sterling
 
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The precise definition can be found here:

http://scienceworld.wolfram.com/astronomy/SchechtersLuminosityFunction.html"

You can think of it roughly as being the number density of L* galaxies, which are Milky Way-sized galaxies.
 
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