期刊
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
卷 -, 期 6, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/1475-7516/2017/06/043
关键词
cosmic web; cosmological simulations; dark matter simulations; gravity
资金
- Wallonia-Brussels Federation [ARC11/15-040]
- Belgian Federal Office for Science, Technical & Cultural Affairs through the Interuniversity Attraction Pole [P7/37]
- U.K. Science and Technologies Facilities Council [ST/N000668/1]
- DFG [SFB-Transregio TRR33]
- European Research Council [646702]
- Science and Technology Facilities Council [ST/N000668/1] Funding Source: researchfish
- STFC [ST/N000668/1] Funding Source: UKRI
Initial conditions for (Newtonian) cosmological N-body simulations are usually set by re-scaling the present-day power spectrum obtained from linear (relativistic) Boltzmann codes to the desired initial redshift of the simulation. This back-scaling method can account for the effect of inhomogeneous residual thermal radiation at early times, which is absent in the Newtonian simulations. We analyse this procedure from a fully relativistic perspective, employing the recently-proposed Newtonian motion gauge framework. We find that N-body simulations for ACDM cosmology starting from back-scaled initial conditions can be self consistently embedded in a relativistic space-time with first-order metric potentials calculated using a linear Boltzmann code. This space-time coincides with a simple N-body gauge for z < 50 for all observable modes. Care must be taken, however, when simulating nonstandard cosmologies. As an example, we analyse the back-scaling method in a cosmology with decaying dark matter, and show that metric perturbations become large at early times in the back-scaling approach, indicating a breakdown of the perturbative description. We suggest a suitable forwards approach for such cases.
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