Run

This section is started with the single line:

[Run]

Run Parameters

verbose=1 [0,1,2]

The verbosity level (how much text is printed to the screen) with the higher numbers representing more info.

num_photons=1e5 [1,1e10]

The number of photons to run at each wavelength point.

do_dust_emission=1 [0,1]

To have the code compute the dust thermal emission (equilibrium and non-equilibrium), set to 1.

energy_conserve_target=0.05 [0.,1.]

The conservation target for the dust emission where 1 is no conservation and 0 is exact conservation. This controls the number of iterations needed to account of dust self-absorption. There is a maximum number of iterations that is currently hard coded to 10.

random_num_seed=987654321

The random number seed determines the initial conditions of the run. Changing this will produce different results (outputs), as the pseudo-random number generator will use the seed to produce random numbers that are used in various parts of Monte Carlo simulation. The independence of runs with different random number seeds is not guaranteed.

repeat_boundary_xy [0,1]

This adds a repeating boundary condition for photons that exit the model grid in the x or y directions. These photons continue along their trajectories, just shifted to the opposite side of the model (i.e., if exiting in the positive x direction, the photon’s x position is set to -x and the photon continues through the model grid).

This option only will work correctly for models that fully fill the main grid - no cells with -0.5 indicating the edge of the model has been reached. The slab geometry meets this criteria. The file geometry can meet this criteria if the file is setup with no -0.5 values.

The repeating xy boundary will cause longer run times as the photon trajectories are longer. These run times can be much longer depending on the optical depths of the model, where low may mean longer than high, depending on the geometry.

Output Details

do_global_output=1 [0,1]

do_image_output=0 [0,1]

The amount of output can be a FITS table of global luminosities and/or images at each wavelength. At least one of these two outputs must be set to 1.

An image is created for each wavelength in your wavelength grid; the number preceding ‘um’ in the filename indicates the wavelength in microns of each image. Furthermore, images are split into dust emission images and stellar emission images. To get the final total image, you need to combine the stellar radiative transfer with the dust emission. The image naming scheme is as follows:

<filename>_de_ge?_w*_*um.fits

These are the images for the dust emission. The ge1 files are the total dust emission, the subsequent (ge2, ge3 files) are it split up between grain types and emission (equilibrium/non-equilibrium).

<filename>_w*_*um.fits

These are the images from the stellar radiative transfer before the dust emission.

The size of the output images (at each wavelength) can be given two ways.

output_image_size=201 [1,5e4]

For square images. Usually used for external observers where the output image is a tangent projection.

output_image_x_size=201 [1,5e4]

output_image_y_size=201 [1,5e4]

For rectangular images. This option may be particularly useful for internal observers. For internal observers, the image is given in (phi, theta) angles. Specifically the x-axis=phi and y-axis=cos(theta).

output_filebase=standard_sphere [any string]

The size base filename of the images.

output_type=ratio [ratio,sbrightness]

The units of the output images are either a ratio to the source luminosity (basically unitless) or as a surface brightness (cm^-2 sr^-1)

output_model_grid=1 [0,1]

Parts of the model grid can be output as a multi-extension FITS files.

Currently, the files output give the tau/pc, the positions of the cell edges, the radiation field, the number of H atoms in each cell, and the wavelength grid.

do_emission_type=1 [0,1]

The output of the dust emission can be separated into emission from grains in equilibrium and non-equilibrium.

do_emission_grain=1 [0,1]

The output of the dust emission can be separated into emission from grains of different compositions (graphite, silicate, PAH, etc.).