Preparing the photon packets initial condition file

Three stand-alone codes are currently available to generate PPIC files for different sources (see main paper for more details):

• a code to spawn photon packets from star particles, taking into account their ages and metallicites and using various SED libraries, PhotonsFromStars

• a code to spawn Lyman−α photons emitted by the gas, taking into account both recombination and collisional contributions, LyaPhotonsFromGas

• a simple code to produce ad-hoc sources which may be used for tests or idealised models, PhotonsFromSourceModel

Emission from stars

The first stand-alone code, PhotonsFromStars, generates photon packets from star particles which represent stellar populations of single ages and metallicities. It has a number of options, set in the parameter file below.

!--------------------------------------------------------------------------------
[PhotonsFromStars]
# input / output parameters
repository = directory_where_ramses_outputs_are
snapnum    = output_number
outputfile = path_to_the_photonsIC_file

# computational domain parameters
star_dom_type      = sphere
star_dom_pos       = 5.000E-01 5.000E-01 5.000E-01
star_dom_rsp       = 3.000E-02
#  star_dom_size      = 3.000E-01
#  star_dom_rin       = 0.000E+00
#  star_dom_rout      = 3.000E-01
#  star_dom_thickness = 1.000E-01

# Particle weights
weight_type        = Mono
weight_input_file  = path_to_the_table_file_with_SSP_weights

# Spectral shape
spec_type               = Gauss
spec_gauss_sigma_kms    = 20.0
#  spec_powlaw_lmin_Ang    = 1.120E+03 ! [A]
#  spec_powlaw_lmax_Ang    = 1.320E+03 ! [A]

# miscelaneous parameters
nPhotonPackets  = 1000000
ranseed         = -100
verbose         = T
!--------------------------------------------------------------------------------

!--------------------------------------------------------------------------------
[ramses]
self_shielding   = F
ramses_rt        = F
verbose          = T
cosmo            = T
use_initial_mass = F
use_proper_time  = F
itemp  = 5
imetal = 6
ihii   = 7
iheii  = 8
iheiii = 9
!--------------------------------------------------------------------------------

Again, this should be compiled in rascas/f90 with make PhotonsFromStars and run with ./PhotonsFromStars params_PFS.cfg.

Lyman−α emission from gas

The second stand-alone code, LyaPhotonsFromGas, generates photon packets which describe Lyman−α emission from the gas.

Ad hoc source models

The simplicity of PPIC files makes it straightforward to write these files with any idealised configuration. An example is the code PhotonsFromSourceModel, which can be used as it is or extended to different configurations.