luminosity function
(LF)
(function giving number of stars or galaxies at different luminosities)
A luminosity function for some type of astronomical object,
is an empirical unnormalized probability density function that yields the number of
them at each possible luminosity.
Example object types are galaxies (galaxy luminosity function)
and globular clusters (globular cluster luminosity function).
For example, the Schechter luminosity function for galaxies
(aka Schechter function, an example of a galaxy luminosity function),
which is a modified power law:
Φ(L)dL = Φ*(L/L*)αexp(-L/L*)d(L/L*)
- L - luminosity.
- dL - differential of the luminosity.
- Φ(L)dL - number density of galaxies with luminosity within interval dL.
- L* - parameter: a luminosity value around which this function is adjusted, i.e., within the function's regime.
- Φ* - parameter: normalization factor: the value of the function at L*.
- α - parameter: exponent that fits observation data.
The parameters are chosen to fit observation. Example case:
- L* = 1.4 × 1010
- Φ* = 1.77 × 10-2
- α = -1.15
Other variations of luminosity functions are
galaxy cluster luminosity functions,
planetary nebula luminosity functions,
and luminosity functions of particular bands, spectral lines,
or the lines of a specific molecule (e.g., carbon monoxide).
It is assumed that luminosity functions might evolve, e.g.,
vary with redshift.
(model,relation,stars,luminosity,galaxies,function)
Further reading:
https://en.wikipedia.org/wiki/Luminosity_function_(astronomy)
https://ned.ipac.caltech.edu/level5/Sept14/Dunlop/Dunlop4.html
https://ned.ipac.caltech.edu/level5/Sept13/Kissler/Kissler7.html
http://lifeng.lamost.org/courses/astr553/Topic04/Lecture_4.html
https://ui.adsabs.harvard.edu/abs/1976ApJ...203..297S/abstract
https://www.astro.umd.edu/~richard/ASTRO620/LumFunction-pp.pdf
http://astronomy.nmsu.edu/aklypin/AST616/LumFunction.pdf
Referenced by pages:
conditional luminosity function (CLF)
globular cluster luminosity function (GCLF)
initial mass function (IMF)
luminosity density
planetary nebula luminosity function (PNLF)
X-ray luminosity function (XLF)
Index