Data Products ============= Overview -------- All simulations in the **Kun Universe** are generated by the modified version of the `Gadget-4` code with 129 different cosmologies. Each simulation evolves :math:`3072^3` particles in a box of :math:`1~h^{-1}\mathrm{Gpc}` on a side. The massive neutrinos are incoporated through the Newtonian-motion gauge (detailed in `Heuschling et al. 2022 `_). All particles are initialized with the second-order Lagrangian Perturbation Theory (2LPT) at the fixed redshift :math:`z = 127`. An isotropic glass-like distribution is applied to pre-initial loads. At small scales, we fix the equivalent Plummer softening length to :math:`\epsilon = 8~h^{-1}\mathrm{kpc}` in comoving coordinates. At large scales, the grid size for Particle-Mesh (PM) force calculation is fixed at :math:`N_\mathrm{grid}=6144`. The maximum allowed time step is set to :math:`\mathrm{max}(\Delta \ln a) = 0.04`. We output **12** snapshots at fixed redshifts of ``z = {3.00, 2.50, 2.00, 1.75, 1.50, 1.25, 1.00, 0.80, 0.50, 0.25, 0.10, 0.00}``. The total storage size for the whole simulation suite is about **3.1 PB**. The directory of each simulation output is named as ``csst/simulation/cXXXX/output/``, where ``XXXX`` is the cosmology index from 0000 - 0128. In the ``KunShan`` cluster, the data is stored in the ``/public/home/chenzhao/`` directory. In the `Gravity `_ cluster in the Department of Astronomy, SJTU, the data is stored in the ``home/cossim/yuyu22/chenzhao/`` directory. The key data products are listed as follows. The corresponding Python analysis scripts is available in the `github repo `_. Particle Data ------------- Snapshot ~~~~~~~~ Full particle samples at **12** redshifts are saved in the HDF5 format, including positions, velocities, and particle IDs. The positions and velocities are stored with the 32-bit float, and the particle IDs are stored with the 64-bit integer. The directory is named as ``snapdir_xxx/snapshot_xxx.*.hdf5``, where ``xxx`` is the snapshot index from 000 - 011 and ``*`` is the file index from 0 - 1023. The 1/64 downsampled particle samples are also available in the ``snapdir_xxx_down64/snapshot_xxx_down64.*.hdf5`` files, where ``xxx`` is the snapshot index from 000 - 011 and ``*`` is the file index from 0 - 1023. Particle Lightcone ~~~~~~~~~~~~~~~~~~ We also save two on-the-fly pyramid particle light-cones up to :math:`z\leq 3` by tiling simulation boxes along the three main axes. Each cone covers :math:`2116\,\mathrm{deg^2}`. Two special line-of-sight directions :math:`\vec{n}_1 = \{ 0.8678,\ 0.3595,\ 0.3431 \}` and :math:`\vec{n}_2 = \{ 0.3595,\ 0.8678,\ 0.3431\}` are selected to dilute the structure repetitions caused by box replication. Files for particle lightcone are saved in the HDF5 format. The directory is named as ``lightcone_xx/conedir_yyyy/conesnap_yyyy.*.hdf5``, where ``xx`` is the lightcone index from 00 - 01, ``yyyy`` is the lightcone index starting from 0000, and `*` is the file index from 0 - 1023. Halo Data --------- FOF-SubFind Halo ~~~~~~~~~~~~~~~~ The Friends-of-Friends (FOF) and SubFind halo/subhalo catalogs are saved in the HDF5 format. We utilize the algorithm integrated in `Gadget-4 `_. It is stored in ``groups_xxx/fof_subhalo_tab_xxx.*.hdf5``, where ``xxx`` is the snapshot index from 000 - 011 and ``*`` is the file index from 0 - 1023. Rockstar Halo ~~~~~~~~~~~~~ The Rockstar halo catalogs are saved in both ASCII format and HDF5 format. We utilize the algorithm integrated in `Rockstar `_. The ASCII format is stored in ``groups_all_rockstar/out_x.list``, where ``x` is the snapshot index from 0 - 11. The HDF5 format is stored in ``groups_xxx_rockstar/rockstar_tab_xxx.*.hdf5``, where ``xxx`` is the snapshot index from 000 - 011 and ``*`` is the file index from 0 - 63. For further information about each halo property (e.g., ``Mvir_all``), we recommand to check the `cosmosim site `_ and `Rockstar Paper `_. Field Data ---------- Matter Density Field ~~~~~~~~~~~~~~~~~~~~ The matter density field is saved in the HDF5 format for each snapshot. The number of mesh grids is :math:`1536^3` and window function is the Cloud-in-Cell (CIC) scheme. The files are named as ``mesh_xxx/mesh_xxx_CIC_Nmesh1536.*.hdf5``, where ``xxx`` is the snapshot index from 000 - 011 and ``*`` is the file index from 0 - 191. Full-sky Mass Map ~~~~~~~~~~~~~~~~~ The full-sky mass map is saved in the HDF5 format with thickness of :math:`50~h^{-1}\mathrm{Mpc}`. The files are named as ``mapsdir_xxx/maps_xxx.*.hdf5``, where ``xxx`` is the snapshot index starting from 000 but ending at different number for different cosmologies. And ``*`` is the file index from 0 - 1023. The map is schemed with the Healpix pixelization with the resolution of :math:`N_{\mathrm{side}} = 8192`. Weak Lensing Convergence Map (Born Approximation) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The weak lensing convergence map is saved in the binary format for :math:`z_s \in [0.5, 3.0]` with distance interval of :math:`50~h^{-1}\mathrm{Mpc}`. The files are named as ``kappas/kappa-nbox*-thickness50-8192.bin``, where ``*`` represents the used number of shells. The corresponding source redshift is ``nbox * thickness``. Table of Data Products ---------------------- Here, we summarize the key data products in the **Kun Universe**. The ``Server`` column indicates the storage location of the data. ``K`` represents the ``KunShan`` cluster, and ``G`` represents the `Gravity `_ cluster in SJTU. The data for each simulation is stored in the ``/public/home/chenzhao/`` directory in the ``KunShan`` cluster and the ``home/cossim/yuyu22/chenzhao/`` directory in the ``Gravity`` cluster. The meanings of ``x`` and ``y`` in the ``File Name`` are shown in the previous sections. The ``Storage Size`` column represents the probable storage size for each cosmological model. According to the different cosmologies, the storage size may vary. +------------------------------+--------+------------------------------------------------+-------------+ | Data Products | Server | File Name | Storge Size | +==============================+========+================================================+=============+ | Snapshot | K | snapdir_xxx/snapshot_xxx.*.hdf5 | ~ 6.6 TB | +------------------------------+--------+------------------------------------------------+-------------+ | Snapshot 1/64 subsample | K & G | snapdir_xxx_down64/snapshot_xxx_down64.*.hdf5 | ~ 132 GB | +------------------------------+--------+------------------------------------------------+-------------+ | Particle Lightcone | K | lightcone_xx/conedir_yyyy/conesnap_yyyy.*.hdf5 | ~ 18 TB | +------------------------------+--------+------------------------------------------------+-------------+ | FOF-SubFind Halo/Subhalo | K & G | groups_xxx/fof_subhalo_tab_xxx.*.hdf5 | ~ 100 GB | +------------------------------+--------+------------------------------------------------+-------------+ | Rockstar Halo/Subhalo (TXT) | K & G | groups_all_rockstar/out_x.list | ~ 300 GB | +------------------------------+--------+------------------------------------------------+-------------+ | Rockstar Halo/Subhalo (HDF5) | G | groups_xxx_rockstar/rockstar_tab_xxx.*.hdf5 | ~ 100 GB | +------------------------------+--------+------------------------------------------------+-------------+ | Matter Density Field | K & G | mesh_xxx/mesh_xxx_CIC_Nmesh1536.*.hdf5 | ~ 156 GB | +------------------------------+--------+------------------------------------------------+-------------+ | Full-sky Mass Map | K & G | mapsdir_xxx/maps_xxx.*.hdf5 | ~ 225 GB | +------------------------------+--------+------------------------------------------------+-------------+ | :math:`\kappa` Map (Born) | K & G | kappas/kappa-nbox*-thickness50-8192.bin | ~ 250 GB | +------------------------------+--------+------------------------------------------------+-------------+ All analysis scripts (:py:attr:`Python`) is available in the `github repo `_.