From f6ce2a9279f645c31b2bed380ab1fbc8402d924a Mon Sep 17 00:00:00 2001 From: Volker Springel <vspringel@mpa-garching.mpg.de> Date: Tue, 15 Jun 2021 15:03:54 +0200 Subject: [PATCH] extended documentation of LightConeDefinitionFile parameter --- documentation/05_parameterfile.md | 50 +++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/documentation/05_parameterfile.md b/documentation/05_parameterfile.md index f231b8f..4f6f849 100644 --- a/documentation/05_parameterfile.md +++ b/documentation/05_parameterfile.md @@ -1047,6 +1047,56 @@ indirectly determines on how many output files the lightcone is distributed. By overriding the constant `LIGHTCONE_ALLOC_FAC` in the `Config.sh`-file, this can be influenced if desired. +The file defining the lightcones has the following format. Each +line defines a separate lightcone, and is defined at least by four +numbers: +<type> <flag> <astart> <aend> + +Here <type> can be either 0, 1, 2, 3, or 4, and defines the geometric +selection of the specific lightcone, according to: 0 = full sky, +1 = one octant, 2 = a pencil beam cone with circular aperture, +3 = a disk like region, 4 = a pencil beam with a square-shaped aperture. + +<astart> sets the far edge of the lightcone to redshift zmax = 1/astart - 1 +<aend> sets the near edge of the lightcone to redshift zend = 1/aend - 1 + +<flag> is normally 0. A value of 1 only makes sense combined with the +SUBFIND_ORPHAN_TREATMENT option and then restricts the output to formerly +most bound particles. + +For type=1 (octant), an additional number <octantnr> with value 0, 1, ..., +or 7 is needed to select the specific octant. + +For type=2 (cone), three additional numbers are expected to define the +principal direction vector of the cone (this does not need to be normalized), +followed by its half opening angle in degrees. + +For type=3 (disk), three additional number are expected that define +the normal of the disk region, followed by a further number defining +its comoving thickness. + +For type=4 (pyramid with square base), first three additional number are +expected to define the direction vector of the pencil beam, then a further +vector is expected that is used to set the orientation of the x-direction +of the patch of sky that is mapped by the lightcone, with the y-direction +being orthogonal to that. Finally, a last number gives the half opening +angle of the pyramid-shaped pencil beam in degrees. + +Multiple lightcones, also of the same type, can be specified if desired. +Note that the output will get extremely large if you select even a moderate +redshift depth, because the code will automatically periodically +replicate the simulation box as needed to cover the specified lightcone +geometry. + +An example for a lightcone definition file could look like this: + +0 0 0.5 1.0 +1 0 0.4 1.0 0 + +This would define a full-sky light cone from z=1 to z=0, and an octant +covering positive x>0,y>0,z>0 from redshift z=1.5 to z=0. + + ------- **LightConeMassMapsNside** 12 -- GitLab