3.3.7.1  :  MHalo

The table stores all the halos from the Millennium simulation in a representation that allows efficient querying for merger histories. For description how these merger trees were constructed see Springel2005a and DeLucia2006b.

columntypeUCDunitdescription
haloID long meta.id;meta.main The identifier of this halo, unique within the full simulation.
subHaloID long meta.id; The id of the sub-halo corresponding to this halo. This is a foreign key to the subhaloId in the MField..FofSubHalo table.
lastProgenitorId long meta.id.assoc Indicator of the last progenitor in the halo merger tree rooted in this halo.
All halos with id between haloId and lastProgenitorId form the merger tree rooted in this halo.
Foreign key to MMHalo.haloId.
treeId long meta.id.parent The unique ID of the L-Galaxies galaxy formation "tree" to which this halo belongs.
See the page on the MPA trees
snapNum int time The snapshot number where this halo was identified.
This column corresponds to the snapnum column in the Snapshots table in MField.
redshift float time The redshift of the snapshot to which this halo belongs.
firstProgenitorId long meta.id.assoc The ID of the main progenitor of this halo.
Also the ID of the "first progenitor" in a linked list representation of the halo merger trees.
nextProgenitorId long meta.id.assoc The ID of the "next progenitor" in the linked list representation of the halo merger trees.
descendantId long meta.id.assoc The haloId of the descendant f this halo in the merger tree. -1 if there is no descendant.
firstHaloInFOFgroupId long meta.id.assoc ID of the halo at the center of the friend-of-friends group to which this halo belongs.
nextHaloInFOFgroupId long meta.id.assoc Id of the "next halo" in the linked list representation of the friend-of-friends grouping.
np int meta.number Number of simulation particles in this halo.
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.
phKey int The Peano-Hilbert index for the position of this halo.
x float pos.cartesian.x Mpc/h The X-coordinate of the position in comoving coordinates.
y float pos.cartesian.y Mpc/h The Y-coordinate of the position in comoving coordinates.
z float pos.cartesian.z Mpc/h The Z-coordinate of the position in comoving coordinates.
zIndex long The "bit-interleaved" or "Z-curve" index, same resolution as phKey.
See the text on spatial indexes.
ix integer pos.cartesian.x Zone index along x-direction, based on 7 bins
See the text on spatial indexes.
iy integer pos.cartesian.x Zone index along y-direction, based on 7 bins
See the text on spatial indexes.
iz integer pos.cartesian.x Zone index along z-direction, based on 7 bins
See the text on spatial indexes.
velX float phys.veloc km/sec The X-component of the peculiar velocity.
velY float phys.veloc km/sec The Y-component of the peculiar velocity.
velZ float phys.veloc km/sec The Z-component of the peculiar velocity.
velDisp float phys.veloc.dispersion km/sec he velocity dispersion of the halo.
vMax float phys.veloc.rotat km/sec Maximum rotational velocity, calculates as the maximum of the expression sqrt(G M(r)/r) where r runs of the particles in the halo.
spinX float phys.veloc.ang (Mpc/h) (km/sec) The X-component of the spin of the halo.
spinY float phys.veloc.ang (Mpc/h) (km/sec) The Y-component of the spin of the halo.
spinZ float phys.veloc.ang (Mpc/h) (km/sec) The Z-component of the spin of the halo.
mostBoundID long meta.id.assoc The id of the most bound particle of this halo.
fileNr int meta.file;meta.id Original file number in which the halo was defined.
subhaloIndex int meta.id.assoc Index of this subhalo in the file identified by fileNr.
halfmassRadius float phys.size.radius Mpc/h Radius containing half of the mass of the halo.