Including Helium in 1-D Radiative Transfer Calculations

Test #2 from the Radiative Transfer Comparison Project (Iliev et al. 2006).

This problem investigates the growth of an HII region around a blackbody source of ionizing photons. The main parameters are:

  • Stellar ionizing photon production rate of \(\dot{Q} = 5 \times 10^{48} \ \text{s}^{-1}\).

  • Stellar spectrum is a \(10^5\) K blackbody.

  • Medium composed of hydrogen only, with a density of \(n_{\text{H}} = 10^{-3} \ \text{cm}^{-3}\).

  • Gas temperature is able to evolve. It is initially set to \(T=100\) K everywhere on the grid.

The ionization and heating rates are computed treating the source’s spectral energy distribution in full. A lengthy discussion of this can be found in Mirocha et al. (2012).

Including helium for pre-existing problem types is as simple as adding 10 to the problem_type, i.e.,

import ares

sim = ares.simulations.RaySegment(problem_type=12)
sim.run()

Now, we initialize an instance of the appropriate analysis class:

and have a look at the temperature profile at 10, 30, and 100 Myr,

ax1 = sim.RadialProfile('Tk', t=[10, 30, 100])

radial profiles of the hydrogen species fractions,

ax2 = sim.RadialProfile('h_1', t=[10, 30, 100], fig=2)
sim.RadialProfile('h_2', t=[10, 30, 100], ax=ax2, ls='--')

and the species fractions for helium:

ax3 = sim.RadialProfile('he_1', t=[10, 30, 100], fig=3)
sim.RadialProfile('he_2', t=[10, 30, 100], ax=ax3, ls='--')
sim.RadialProfile('he_3', t=[10, 30, 100], ax=ax3, ls=':')