Commit f6ce2a92 authored by Volker Springel's avatar Volker Springel
Browse files

extended documentation of LightConeDefinitionFile parameter

parent 6abe36fa
......@@ -1047,6 +1047,56 @@ indirectly determines on how many output files the lightcone is
distributed. By overriding the constant `LIGHTCONE_ALLOC_FAC` in the
``-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
<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
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
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