## MDPL2

The MultiDark Planck 2 simulation belongs to the series of MultiDark simulations with Planck cosmology. It is kin to the MDPL simulation, with the same box size, cosmological parameters and particle resolution, but a different initial seed.

If you are in doubt whether to use MDPL or MDPL2, we recommend to use MDPL2, since there will be more data products available for this simulation in the future (e.g. Rockstar-catalogues).

Please give proper Credits when using data from this simulation.

### Details

Box size | 1 Gpc/h | side length of the cosmological cube |

Number of particles | 3840^{3} |
total number of dark matter particles |

Mass resolution | 1.51*10^{9} M_{sun}/h |
mass of one dark matter particle |

Force resolution | 13 kpc/h (at high z) – 5 kpc/h (low z) | physical force resolution |

Initial redshift | 120 | redshift at which the simulation started |

Cosmology | ||

h | 0.6777 | Hubble parameter |

Ω_{Λ} |
0.692885 | density parameter for dark energy |

Ω_{m} |
0.307115 | density parameter for matter (dark matter+baryons) |

Ω_{b} |
0.048206 | density parameter for baryonic matter |

n | 0.96 | normalization of the Power spectrum |

σ_{8} |
0.8228 | amplitude of mass density fluctuation in 8 Mpc/h sphere (at redshift z=0) |

Other constants | ||

G | 6.67428 * 10^{-8} cm^{3} g^{-1} s^{-2} |
Gravitational constant (Rev. Mod. Phys. 80 (2008) 633-730) |

1 Mpc | 30.85677 * 10^{23} cm |
1 Mpc in cm |

M_{sun} |
1.98892 ± 0.00025 10^{33} g |
Solar mass (Physics Reports 281 (1997) 309) |

### MDPL2 data in the database

The following table provides an overview on the database tables which are available for this simulation. For each table, a link to its “table type” is given, which leads to a page explaining the individual columns of the table in more detail.

Several tables may contain a Peano-Hilbert key (phkey) for each row, which can be constructed from the position using the hilbert key function. If not indicated otherwise, the hilbert order for this simulation is 10, i.e. there are 2^{10} = 1024 cells per dimension.

Database table | Table type | Short description |
---|---|---|

AvailHalos | AvailHalos | Gives an overview on the snapshots, for which halo data are stored in the halo catalogues tables. In particular, it gives the number of halos/FOF groups for each snapshot. |

FOF | FOF | Main Friends-of-Friends catalogue for all available snapshots, level 0. Similar to the MDPL simulation, a relative linking length of 0.20 was used (like in MDR1.FOFc table).`fofId = (snapnum*10+level)*10` |

FOF1-FOF4 | FOF | Friends-of-Friends catalogue for all available snapshots, same as FOF-table, but for smaller (relative) linking lengths (factor 2 for each step), levels 1 (linking length 0.10) to 5 (linking length 0.00625). Thus these tables contain substructures of the FOF groups. |

LinkLength | LinkLength | Overview on levels for FOF groups and corresponding linking lengths (for FOF, FOF1 – FOF4 tables) |

Redshifts | Redshifts | Overview on snapshot numbers (snapnum) and corresponding redshifts. In addition to the usual Redshifts-table columns, for SMDPL this table also contains a column `orig_snapnum` , which refers to the original snapshot number of the files. This differs from `snapnum` , because the simulation was run twice, first with more outputs at later times and second with more outputs at early times. |

Rockstar | Rockstar | ROCKSTAR halo catalogue with consistent merger trees for all available snapshots. |