The Last Objects Simulation Suite (LOSS) — Primary Sample

Le résumé fourni par la source

Halo catalogues, matter power spectra and initial-condition inputs from the Primary Sample of LOSS, the Last Objects Simulation Suite: five cosmological N-body simulations run with AsymptoticGadget4, a fork of GADGET-4. The five boxes share a single random seed and an identical CLASS transfer function, so they are phase-matched with fixed mode amplitudes, and box size is the independent variable of the sample. All five are evolved far past the present day, to a = 100, into the regime where accelerated expansion has largely ended the growth of structure. Contents Per simulation: fof_subhalo_tab snapshots 000–074, subhalo_desc 000–073, and subhalo_prog 001–074, where snapshot 074 is a = 100 in all five. 7805 files, 100.18 GB uncompressed, shipped as five gzipped tar archives totalling 40.08 GB; each unpacks to a single LOSS_ / directory. Simulation Layout Files Archive Groups at a = 100 Subhaloes at a = 100 Uniform_L256_N256 (sandbox) flat 223 0.22 GB 32,275 31,094 Uniform_L32_N1024 16-piece 3568 6.01 GB 505,089 622,092 Uniform_L128_N1024 16-piece 3568 7.88 GB 813,540 906,510 Uniform_L512_N1024 flat 223 11.17 GB 1,487,085 1,498,891 Uniform_L2048_N1024 flat 223 14.80 GB 2,651,012 2,441,891 Two further files accompany the archives: LOSS_power_spectra_and_inputs.tar.gz (30 MB) and LOSS_RELEASE_MANIFEST.json, a per-file index of sizes and checksums. Particle snapshots and initial-condition particle data are not included. Matter power spectra and initial-condition inputs LOSS_power_spectra_and_inputs.tar.gz holds GADGET-4's measured matter power spectrum at every output (powerspec_000–074.txt, 75 per simulation), the matching inputspec_snapshot.txt, and — once for the sample — the tabulated CLASS spectrum the initial conditions were drawn from, together with the output-time ladder snapshot_epochs.txt. Those last two are the files each catalogue names in its /Parameters group. The archive is organised one directory per simulation, and the README inside documents the formats, which are not self-describing. Using the data Each catalogue is an HDF5 file with /Header, /Group and /Subhalo, and the complete run configuration under /Parameters and /Config. Groups carry GroupPos, GroupMass, GroupLen and spherical-overdensity masses and radii (Group_M_Crit200, Group_M_Mean200, Group_M_TopHat200, Group_M_Crit500 and the matching Group_R_*); subhaloes carry SubhaloPos, SubhaloMass, SubhaloVmax, SubhaloHalfmassRad, SubhaloSpin and SubhaloVelDisp, with SubhaloGroupNr, GroupFirstSub and GroupNsubs linking the two. Lengths are comoving Mpc/h, masses 1010 M☉/h and velocities km/s, as set by the unit parameters in /Parameters. The flat-layout runs write one file per snapshot; L32 and L128 split each snapshot into 16 pieces under groups_NNN/, which concatenate in piece order to the totals given by /Header/Ngroups_Total and /Header/Nsubhalos_Total. Mass functions, clustering and abundance statistics therefore need no more than an HDF5 reader and the periodic box side in /Header/BoxSize. For the spectra, inputspec_snapshot.txt gives the linear input table with its growth factor at z = 99, so a measured powerspec_NNN.txt can be compared directly against linear theory scaled to that output; the folded sections of each file extend the wavenumber range by factors of 16 and 256 beyond the unfolded one. To reproduce or extend the runs, /Parameters holds the full parameter set including the random seed, and the shipped input spectrum and output ladder are the two external files it references — AsymptoticGadget4 regenerates the initial conditions from them. Merger trees are likewise not shipped because the same code rebuilds them exactly from these catalogues: restart flag 8 (RST_MAKETREES) reads only fof_subhalo_tab, subhalo_desc and subhalo_prog, and no particle snapshots. The code is archived at https://doi.org/10.5281/zenodo.22099530. Cosmology and configuration Ωm = 0.306, ΩΛ = 0.694, Ωb = 0.0487, h = 0.68, σ8 = 0.804, ns = 0.969, identical in all five runs. FOF linking length 0.28. All five share an identical GADGET-4 /Config and use standard spherical-overdensity masses; the softening scales with box size and is recorded per run in /Parameters. The catalogues were produced by AsymptoticGadget4. This dataset accompanies the thesis Asymptotic Assembly Histories (forthcoming).

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.