Physics ParametersΒΆ

radiative_transfer
  1. No astrophysical sources.
  2. Includes ionization/heating from astrophysical sources.

Default: 1

compton_scattering
  1. OFF
  2. Include Compton scattering between free electrons and CMB.

Default: 1

secondary_ionization

Determine what fraction of photo-electron energy gets deposited in various channels, such as heat, ionization, and excitation.

  1. All photo-electron energy deposited as heat.
  2. Compute using fits of Shull & vanSteenberg (1985).
  3. Compute using energy-dependent fits of Ricotti, Gnedin, & Shull (2002).
  4. Compute using look-up tables of Furlanetto & Stoever (2010).

Default: 1

fXh

Set fractional heating by photo-electrons by-hand. Currently must be a constant. Will override choice of secondary_ionization if supplied.

Default: None

clumping_factor

Multiplicative enhancement to the recombination rate.

Default: 1

approx_He
See following table for possible behaviors depending on value of include_He. Default: False
include_He approx_He description
False False Neglects helium entirely
True True Set \(x_{\text{HeII}} = x_{\text{HII}}\), and set \(x_{\text{HeIII}} = 0\)
True False Solve for helium self-consistently
approx_sigma
  1. Compute bound-free absorption cross sections via fits of Verner et al. (1996).
  2. Approximate cross-sections as \(\sigma \propto \nu^{-3}\)

Default: 0

approx_lwb
  1. Solves RTE (i.e., full “sawtooth” background).
  2. Assume flat spectrum between Lyman-\(\alpha\) and the Lyman limit.

Default: 1

approx_xrb
  1. Solves RTE.
  2. Heating due to instantaneous X-ray luminosity.

Default: 1

discrete_lwb
  1. Performs integrals numerically using continuous functions for integrands (very slow)
  2. Integrates transfer equation over discrete set of points.

Default: 1

discrete_xrb
  1. Performs integrals numerically using continuous functions for integrands (very slow)
  2. Integrates transfer equation over discrete set of points.

Default: 1

approx_Salpha
  1. Not implemented
  2. Assume \(S_{\alpha} = 1\)
  3. Use formulae of Chuzhoy, Alvarez, & Shapiro (2005).
  4. Use formulae of Furlanetto & Pritchard (2006)

Default: 1

lya_nmax
Default: 23
lya_injected

Include photons injected at line-center?

Default: True

lya_continuum

Include photons redshifting into the blue-wing of the Lyman-\(\alpha\) line?

Default: True

recombination

Which recombination method to use? Can be "A", "B", or 0, the first two options being standard case-A or case-B recombination, whereas the last option artificially turns off recombinations (useful for analytic tests).

Default: B