olnon

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Computes a free-free spectrum based on Olnon (1975) models.

Usage:

import olnon
olnon.olnon(Te, diameter, ne, Dkpc, filename='olnon.dat', doplot=False, 
          freqs=[], ylimits=[], model='truncatedPowerLaw', computeFWHM=False)
Inputs:
  • Te: electron temperature in K
  • diameter = diameter in AU of the central region of constant density
  • ne = central density
  • Dkpc = distance in kpc
  • filename = the output ASCII file containing the spectrum
  • doplot: create a pylab plot
  • freqs: the grid of frequencies to calculate (default is 1-1000 GHz)
  • ylimits: y-axis limits of the resulting plot
  • model: 'cylinder', 'uniformSphere', 'gaussian', 'powerLaw', or 'truncatedPowerLaw' (the latter two use r^-2)
Returns:
  1. ) array of frequencies in GHz
  2. ) array of flux densities in Jy
  3. ) the expected FWHM in AU (i.e. diameter containing half the flux) only relevant if computeFWHM==True

Examples:

CASA <26>: freq, flux, fwhm = olnon.olnon(10000, 1000, 1e6, 1.3, computeFWHM=True)
Total flux density = 8.778397
radius of half flux = 1.226488 = 0.002973 pc.  FWHP = 0.943452 arcsec = 1226.487832 AU
The following example shows how to generate Figure 3 from Olnon, where:
CASA <27>: a=olnon.olnon(10000, 1000, 1e6, 1.3, doplot=True, model='all')
Wrote fnu_vs_nu.png
Color key:
  • black=Model I = uniform cylinder
  • blue = Model II = uniform sphere
  • green = Model III = Gaussian
  • red = Model IV = power law (r^-2)
  • orange = Modle V = truncated power law (r^-2)
fnu_vs_nu.png -- ToddHunter - 2015-12-04
Topic attachments
I AttachmentSorted ascending Action Size Date Who Comment
fnu_vs_nu.pngpng fnu_vs_nu.png manage 32 K 2015-12-04 - 14:26 ToddHunter Reproduction of Figure 3 in Olnon 1975
Topic revision: r1 - 2015-12-04, ToddHunter
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