AIfA,University of Bonn



What does LIGER do?

LIGER takes a sequence of outputs from Newtonian N-body simulations and computes the position of any targets relative to a given observer.
The code takes into account the leading-order redshift-space distortions as predicted by General Relativity and calculates the magnification for each galaxy.
LIGER can process the position of simulated galaxies, galaxies from semi-analytical models or directly the simulation particles.






What does LIGER give as output?

LIGER outputs the observed distribution of targets within the specified redshift range.
Additionally, a catalogue with the real-space light cone is saved.
This makes LIGER very flexible: you can compute any observable from the output of LIGER.

In the example the observed galaxy density in a wedge is computed in real- (left) and redshift-space (right) using LIGER.
For this example we let LIGER compute the observed distribution of matter particles and show the galaxy density as the biased matter density.


These two images present the difference between the real- and redshift-space, split in different contributions.
The left panel shows a pronounced tangential pattern, due to the well known Kaiser squashing effect which is usually accounted for in mock galaxy catalogues.
The right panel indicated a more complex distortion with radially coherent patterns.
This originates from additional redshift-space distortions depending on the line of sight integral of the potential and its derivatives.





Download LIGER

LIGER is available for download from GitLab here.
You can also use GitHub to post issues about the code or, if you prefer, contact us via email .