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Power-Law Shell

Extends the spherical shell with radial power-law profiles for density and velocity: v(r) ~ r^powerlaw_index_velocity and rho(r) ~ r^powerlaw_index_density.

When conserve_column_density is enabled, the density profile is rescaled so that the total column density matches that of a uniform shell with the same mean density. This makes power-law and uniform shells comparable at the same optical depth.

Full configuration
powerlaw_shell.yaml
dataset_type: 'powerlaw_shellmodel'
driver_type: 'mcrtsimulation'
device: "cpu"

powerlaw_shellmodel:
  boxsize: 3.086e21
  inner_radius: 0.01
  outer_radius: 0.1
  temperature: 20000.0
  density: 0.078098                # interpreted as mean density
  outflow_velocity: 200e5          # cm/s at outer_radius
  powerlaw_index_velocity: 1.0     # v(r) ~ r^1
  powerlaw_index_density: -2.0     # rho(r) ~ r^-2
  conserve_column_density: true    # rescale to match uniform shell column

mcrtsimulation:
  outputpath: output
  overwrite: true
  linename: Lya
  nphotons_max: 100000
  nphotons_step_max: 100000
  nsteps_per_photon_max: 10000000
  xcrit: 0.0
  acc_scheme: Smith15
  max_step: 0.0001
  emissionmodel:
    mode: "singlesource"
    singlesource:
      nphotons: 10000
      lum_total: 1e42
      position: [0.5, 0.5, 0.5]
  outputprocessors:
    - type: "photon"
      active: true