Problem Types

There are several pre-defined problem types one can access via the parameter ptype. Note that you can also grab the parameters for a given problem type using the Parameter Bundles machinery. For example,

import ares
pars = ares.util.ParameterBundle('prob:101')

will return a dictionary of parameters for problem_type=101.

ptype \(\leq 20\)

These are all 1-D radiative transfer problems. Will document eventually!

ptype \(\geq 100\)

These are all uniform background / reionization / global 21-cm problems.

100

Blank slate global 21-cm signal problem – no default populations will be initialized, and all “control parameters” take on their default values. Basically this means that the simplest solvers / assumptions will be adopted for everything. Only use this if you know what you’re doing!

101

Simple global 21-cm signal problem in which the Ly-\(\alpha\), LyC, and X-ray production is proportional to the rate of collapse onto all halos exceeding a minimum virial temperature threshold (pop_Tmin) or mass (pop_Mmin). The main free parameters are:

  • pop_yield{0}: Number of LW photons emitted per baryon of star formation. Stellar spectrum assumed flat.

  • pop_yield{1}: Normalization of the X-ray luminosity star-formation rate relation in the 0.5-8 keV band.

  • pop_yield{2}: Number of LyC photons emitted per baryon of star formation.

  • pop_fesc{2}: Escape fraction of LyC radiation.

  • pop_Tmin{0}: Minimum virial temperature of star-forming halos. Note that pop_Tmin{1} and pop_Tmin{2} are automatically linked to pop_Tmin{0}.

Note

In earlier versions of ARES these parameters were denoted more simply as Nlw, fX, Nion, fesc, and Tmin. You can still use this approach (i.e., this shouldn’t break backward compatibility), though in the future this may not be true.

102

Slightly more advanced global 21-cm signal problem in which the Ly-\(\alpha\), LyC, and X-ray production is still proportional to the rate of collapse onto all halos exceeding a minimum virial temperature threshold (pop_Tmin) or mass (pop_Mmin), but the photon production efficiencies are calculated from a stellar synthesis model. The main difference between this problem and problem 101 is that the LW and LyC efficiencies are no longer independent. As a result, there are only two source populations: one stellar and one for X-rays. The main parameters are slightly different as a result:

  • pop_sed{0}: Spectral energy distribution of stellar populations. By default, this is eldridge2009, i.e., the BPASS version 1.0 models.

  • pop_Z{0}: Stellar metallicity.

  • pop_fesc{0}: Escape fraction of LyC radiation.

  • pop_yield{1}: Normalization of the X-ray luminosity star-formation rate relation in the 0.5-8 keV band.

  • pop_Tmin{0}: Minimum virial temperature of star-forming halos. Note that pop_Tmin{1} is automatically linked to pop_Tmin{0}.