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arXiv · 1601.02012

RAY-RAMSES: a code for ray tracing on the fly in N-body simulations

Alexandre Barreira·Claudio Llinares·Sownak Bose·Baojiu Li
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Abstract

We present a ray tracing code to compute integrated cosmological observables on the fly in AMR N-body simulations. Unlike conventional ray tracing techniques, our code takes full advantage of the time and spatial resolution attained by the N-body simulation by computing the integrals along the line of sight on a cell-by-cell basis through the AMR simulation grid. Moroever, since it runs on the fly in the N-body run, our code can produce maps of the desired observables without storing large (or any) amounts of data for post-processing. We implemented our routines in the RAMSES N-body code and tested the implementation using an example of weak lensing simulation. We analyse basic statistics of lensing convergence maps and find good agreement with semi-analytical methods. The ray tracing methodology presented here can be used in several cosmological analysis such as Sunyaev-Zel'dovich and integrated Sachs-Wolfe effect studies as well as modified gravity. Our code can also be used in cross-checks of the more conventional methods, which can be important in tests of theory systematics in preparation for upcoming large scale structure surveys.

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Alexandre Barreira, Claudio Llinares, Sownak Bose, Baojiu Li. 2016-08-20. RAY-RAMSES: a code for ray tracing on the fly in N-body simulations. https://doi.org/10.1088/1475-7516%2F2016%2F05%2F001

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