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.
| column | type | UCD | unit | description |
|---|
| 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.
NB this value is only defined for halos with haloId=firstHaloInFOFgroupId. |
| 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.
NB this value is only defined for halos with haloId=firstHaloInFOFgroupId. |
| 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.
NB this value is only defined for halos with haloId=firstHaloInFOFgroupId. |
| 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.
|
