3.3.10.1  :  FoF

This table contains the FoF group catalogues for all 64 snapshots of the Millennium Run (MR). Subhalos identified within in these groups are listed in the Subhalo table.

columntypeUCDunitdescription
FoFID long meta.id;meta.main The ID of this FoF group, unique within the full simulation.
NumSubgroups int meta.number Number of subhalos in this FoF group.
FirstSubhaloID long meta.id.assoc The unique ID of the most massive subhalo in this FoF group. This corresponds to an entry in the Subhalo table.
np int meta.number Number of simulation particles in this FoF group.
SnapNum int time The snapshot number where this FoF group was identified.
Redshift float time The redshift of the snapshot to which this FoF group belongs.
x float pos.cartesian.x 1/h Mpc x-component position
y float pos.cartesian.y 1/h Mpc y-component position
z float pos.cartesian.z 1/h Mpc z-component position
m_Mean200 float phys.mass 1010 Msun/h The mass within the radius where the halo has an overdensity 200 times the mean density of the simulation.
m_Crit200 float phys.mass 1010 Msun/h The mass within the radius where the halo has an overdensity 200 times the critical density of the simulation.
m_TopHat float phys.mass 1010 Msun/h The mass within the radius where the halo has an overdensity corresponding to the value at virialisation in the top-hat collapse model for this cosmology.
r_Mean200 float phys.radius Mpc/h The radius within which the halo has an overdensity 200 times the mean density of the simulation.
r_Crit200 float phys.radius Mpc/h The radius within which the halo has an overdensity 200 times the critical density of the simulation.
r_TopHat float phys.radius Mpc/h The mass radius within which the halo has an overdensity corresponding to the value at virialisation in the top-hat collapse model for this cosmology.
phKey integer Peano-Hilbert key, (bits=8), for position in 500/h Mpc box. See the text on spatial indexes.
zIndex integer The "bit-interleaved" or "Z-curve" index, corresponding to this halo's position. Same resolution as phKey. See the text on spatial indexes.
ix integer pos.cartesian.x Zone index along x-direction, based on 50 bins. See the text on spatial indexes.
iy integer pos.cartesian.y Zone index along y-direction, based on 50 bins. See the text on spatial indexes.
iz integer pos.cartesian.y Zone index along z-direction, based on 50 bins. See the text on spatial indexes.
random float A random number between 0 and 1000000. See the section on random sampling.