yt.analysis_modules.absorption_spectrum.absorption_line module

Absorption line generating functions.

yt.analysis_modules.absorption_spectrum.absorption_line.tau_profile(lambda_0, f_value, gamma, v_doppler, column_density, delta_v=None, delta_lambda=None, lambda_bins=None, n_lambda=12000, dlambda=0.01)[source]

Create an optical depth vs. wavelength profile for an absorption line using a voigt profile.

Parameters:
  • lambda_0 (float in angstroms) – central wavelength.
  • f_value (float) – absorption line f-value.
  • gamma (float) – absorption line gamma value.
  • v_doppler (float in cm/s) – doppler b-parameter.
  • column_density (float in cm^-2) – column density.
  • delta_v (float in cm/s) – velocity offset from lambda_0. Default: None (no shift).
  • delta_lambda (float in angstroms) – wavelength offset. Default: None (no shift).
  • lambda_bins (array in angstroms) – wavelength array for line deposition. If None, one will be created using n_lambda and dlambda. Default: None.
  • n_lambda (int) – size of lambda bins to create if lambda_bins is None. Default: 12000.
  • dlambda (float in angstroms) – lambda bin width in angstroms if lambda_bins is None. Default: 0.01.
yt.analysis_modules.absorption_spectrum.absorption_line.voigt(a, u)
yt.analysis_modules.absorption_spectrum.absorption_line.voigt_old(a, u)[source]
NAME:
VOIGT
PURPOSE:
Implementation of Voigt function
CATEGORY:
Math
CALLING SEQUENCE:
voigt=Voigt(a,u)
INPUTS:

A = Voigt “A” parameter. U = Frequency in units of the Doppler frequency.

The line profile “Phi(v)”, the doppler width “Delv”, the voigt parameter “a”, and the frequency “u” are given by:

Phi(v) = Voigt(a,u)/[ Delv * sqrt(pi) ] Delv = Vo/c * sqrt[ 2kT/m ] u = V - Vo / Delv a = GAMMA / [ Delv * 4pi ] Gamma = Gu + Gl + 2*Vcol “Gu” and “Gl” are the widths of the upper and lower states “Vcol” is the collisions per unit time “Vo” is the line center frequency

OUTPUTS:
An array of the same type as u
RESTRICTIONS:
U must be an array, a should not be. Also this procedure is only valid for the region a<1.0, u<4.0 or a<1.8(u+1), u>4, which should be most astrophysical conditions (see the article below for further comments
PROCEDURE:
Follows procedure in Armstrong JQSRT 7, 85 (1967) also the same as the intrinsic in the previous version of IDL
MODIFICATION HISTORY:
  1. Murthy, Mar 1990 (adapted from the FORTRAN program of Armstrong)
    Sep 1990 (better overflow checking)
yt.analysis_modules.absorption_spectrum.absorption_line.voigt_scipy(a, u)[source]