This is the N-body simulations 3D images dataset used in the following paper:

  • Scalable Generative Adversarial Networks for Multi-dimensional Images Ankit Srivastava, Nathanaël Perraudin, Aurelien Lucchi, Tomasz Kacprzak, Thomas Hofmann, Alexandre Refregier, Adam Amara

The dataset does not contain the Nbody simulations as they have a very large size. Instead, we sliced the space into 256 x 256 x 256 cubical areas and counted the number of particules in each area. The result are 3D histogram, where the number of particles is a proxy for matter density.

Note that a the same Nbody simulation were used in this paper, but with a different way of building the histogram.

  • Fast Cosmic Web Simulations with Generative Adversarial Networks Andres C Rodriguez, Tomasz Kacprzak, Aurelien Lucchi, Adam Amara, Raphael Sgier, Janis Fluri, Thomas Hofmann, Alexandre Réfrégier https://arxiv.org/abs/1801.09070v1

N-body simulation evolves a cosmological matter distribution over time, starting from soon after the big bang. It represents matter density distribution as a finite set of massive particles, typically order of trillions. The positions of these particles are modified due to gravitational forces and expansion of the cosmological volume due to cosmic acceleration. N-body simulations use periodic boundary condition, where particles leaving the volume on one face enter it back from the opposite side.

Short description of the data generation from Rordiguez et al. 2018:

We created N-body simulations of cosmic structures in boxes of size 100 Mpc and 500 Mpc with 512^3 and 1,024^3 particles respectively. We used L-PICOLA [21] to create 10 and 30 independent simulation boxes for both box sizes. The cosmological model used was ΛCDM (Cold Dark Matter) with Hubble constant H0 = 100, h = 70 km s−1 Mpc−1, dark energy density Omega_Lambda = 0.72 and matter density Omega_m = 0.28. We used the particle distribution at redshift z = 0.

The configuration used for L-Picola is as follows:

$ cat run_parameters.dat

% =============================== % % This is the run parameters file % % =============================== %

% Simulation outputs % ================== OutputDir /cluster/scratch/jafluri/AndresBoxes2/Box_350Mpch_0/ % Directory for output. FileBase out % Base-filename of output files (appropriate additions are appended on at runtime) OutputRedshiftFile /cluster/scratch/jafluri/AndresBoxes2/Box_350Mpch_0/output_redshift.dat % The file containing the redshifts that we want snapshots for NumFilesWrittenInParallel 16 % limits the number of files that are written in parallel when outputting.

% Simulation Specifications % ========================= UseCOLA 1 % Whether or not to use the COLA method (1=true, 0=false). Buffer 3 % The amount of extra memory to reserve for particles moving between tasks during runtime. Nmesh 2048 % This is the size of the FFT grid used to compute the displacement field and gravitational forces. Nsample 1024 % This sets the total number of particles in the simulation, such that Ntot = Nsample^3. Box 350 % The Periodic box size of simulation. Init_Redshift 9.0 % The redshift to begin timestepping from (redshift = 9 works well for COLA) Seed 1020 % Seed for IC-generator SphereMode 0 % If "1" only modes with |k| < k_Nyquist are used to generate initial conditions (i.e. a sphere in k-space), % otherwise modes with |k_x|,|k_y|,|k_z| < k_Nyquist are used (i.e. a cube in k-space).

WhichSpectrum 2 % "0" - Use transfer function, not power spectrum % "1" - Use a tabulated power spectrum in the file 'FileWithInputSpectrum' % otherwise, Eisenstein and Hu (1998) parametrization is used % Non-Gaussian case requires "0" and that we use the transfer function

WhichTransfer 0 % "0" - Use power spectrum, not transfer function % "1" - Use a tabulated transfer function in the file 'FileWithInputTransfer' % otherwise, Eisenstein and Hu (1998) parameterization used % For Non-Gaussian models this is required (rather than the power spectrum)

FileWithInputSpectrum files/input_spectrum.dat % filename of tabulated input spectrum (if used) % expecting k and Pk

FileWithInputTransfer files/input_transfer.dat % filename of tabulated transfer function (if used) % expecting k and T (unnormalized)

% Cosmological Parameters % ======================= Omega 0.276 % Total matter density (CDM + Baryons at z=0). OmegaBaryon 0.045 % Baryon density (at z=0). OmegaLambda 0.724 % Dark Energy density (at z=0) HubbleParam 0.7 % Hubble parameter, 'little h' (only used for power spectrum parameterization). Sigma8 0.811 % Power spectrum normalization (power spectrum may already be normalized correctly). PrimordialIndex 0.961 % Used to tilt the power spectrum for non-tabulated power spectra (if != 1.0 and nongaussian, generic flag required)

% Timestepping Options % ==================== StepDist 0 % The timestep spacing (0 for linear in a, 1 for logarithmic in a) DeltaA 0 % The type of timestepping: "0" - Use modified COLA timestepping for Kick and Drift. Please choose a value for nLPT. % The type of timestepping: "1" - Use modified COLA timestepping for Kick and standard Quinn timestepping for Drift. Please choose a value for nLPT. % The type of timestepping: "2" - Use standard Quinn timestepping for Kick and Drift % The type of timestepping: "3" - Use non-integral timestepping for Kick and Drift nLPT -2.5 % The value of nLPT to use for modified COLA timestepping

% Units % ===== UnitLength_in_cm 3.085678e24 % defines length unit of output (in cm/h) UnitMass_in_g 1.989e43 % defines mass unit of output (in g/h) UnitVelocity_in_cm_per_s 1e5 % defines velocity unit of output (in cm/sec) InputSpectrum_UnitLength_in_cm 3.085678e24 % defines length unit of tabulated input spectrum in cm/h. % Note: This can be chosen different from UnitLength_in_cm