barak.absorb.calctau¶
- barak.absorb.calctau(vel, wa0, osc, gam, logN, b, debug=False, verbose=True)[source]¶
Returns the optical depth (Voigt profile) for a transition.
Given an transition with rest wavelength wa0, osc strength, natural linewidth gam; b parameter (doppler and turbulent); and log10 (column density), returns the optical depth in velocity space. v is an array of velocity values in km/s. The absorption line must be centred at v=0.
Parameters : vel : array of floats, shape (N,)
Velocities in km/s.
wa0 : float
Rest wavelength of transition in Angstroms.
osc : float
Oscillator strength of transition (dimensionless).
gam : float
Gamma parameter for the transition (dimensionless).
logN : float:
log10 of the column density in absorbers per cm^2.
b : float
b parameter (km/s).
Returns : tau : array of floats, shape (N,)
The optical depth as a function of vel.
Notes
The step size for vel must be small enough to properly sample the profile.
To map the velocity array to some wavelength for a transitions with rest wavelength wa0 at redshift z:
>>> z = 3.0 >>> wa = wa0 * (1 + z) * (1 + v/c_kms)