October 1, 2025 Dataset Open Access

Data: Nonlinear Matter Power Spectrum from relativistic N-body Simulations: ΛsCDM versus ΛCDM

Akarsu, Özgür; Di Valentino, Eleonora; Vyskocil, Jiri; Yılmaz, Ezgi; Yükselci, A. Emrah; Zhuk, Oleksandr

Matter power spectra presented in the associated paper are obtained from the datasets separately generated from N-body simulations with the relativistic code gevolution [1], and from calculations with the linear Boltzmann code CLASS [2], for matching cosmological best-fit parameters and background cosmologies. Regarding the latter element, we study two cases that are the concordance Lambda-Cold Dark Matter (ΛCDM) model and a late-time modification with a sign-switching vacuum sector (ΛsCDM), and for each model there are two best-fit parameter sets, derived from a Planck-only and a combined "full" dataset. 

P(k) (power spectra) outputs from gevolution are computed at the four redshifts z=15, 2, 1, 0 for the density contrasts of total matter (CDM, baryons, and massive neutrinos) as well as CDM-baryons (cb)-only. A detailed explanation of how the matter sector is handled in simulations is available in the main paper. All runs are carried out in boxes of L=2080 Mpc/h with 0.5 h/Mpc resolution.

Power spectra based on CLASS outputs are obtained from the transfer functions of CDM and baryons, and the respective background densities at z=15, 2, 1, 0. CLASS dataset for the latter is shown only up to z=100.

1. J. Adamek, D. Daverio, R. Durrer, and M. Kunz, gevolution: a cosmological N-body code based on General Relativity, JCAP 07, 053. arXiv:1604.06065 [astro-ph.CO].

2. D. Blas, J. Lesgourgues, and T. Tram, The Cosmic Linear Anisotropy Solving System (CLASS) II: Approximation schemes, JCAP 07, 034. arXiv:1104.2933 [astro-ph.CO].