This table contains merger trees for the Millennium Run (MR) constructed using the friends of
friends (FoF) group catalogues. The merger trees are stored in
the same format as the DHalo trees. Each FoFHalo contains zero or
more subhalos, and the FoFSubhalo table can be used to find all the
subhalos that belong to a FoFHalo.
| column | type | UCD | unit | description |
|---|
| FoFHaloID |
long |
meta.id;meta.main |
|
The ID of this FoFHalo, unique within the full simulation.
|
| DescendantId |
long |
meta.id.assoc |
|
The ID of the descendant of this FoFHalo in the merger tree.
|
| LastProgenitorId |
long |
meta.id.assoc |
|
Indicator of the last progenitor in the FoFHalo merger tree
rooted in this FoFHalo.
All FoFHalos with id between ID
and LastProgenitorId form the merger tree rooted in this
FoFHalo. |
| TreeId |
long |
meta.id.parent |
|
The unique id of the FoFHalo merger tree to which this FoFHalo belongs.
|
| FirstSubhaloID |
long |
meta.id.assoc |
|
The unique id of the most massive subhalo in this
FoFHalo. This corresponds to the SubhaloID column in the
Subhalo table.
|
| np |
int |
meta.number |
|
Number of simulation particles in this FoFHalo. This is
equal to the total number of particles in the constituent
subhalos of the FoFHalo.
|
| NSubhalos |
int |
meta.number |
|
Number of subhalos in this FoFHalo.
|
| SnapNum |
int |
time |
|
The snapshot number where this FoFHalo was identified.
|
| Redshift |
float |
time |
|
The redshift of the snapshot to which this FoFHalo belongs.
|
| FirstProgenitorID |
long |
meta.id.assoc |
|
The ID of the most massive progenitor of the FoFHalo
|
| EndMainBranchID |
long |
meta.id.assoc |
|
The ID of the halo at the end of the main progenitor branch of this halo.
|
| phKey |
integer |
|
|
Peano-Hilbert key, (bits=5), for position in 62.5/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 7 bins. See the text on spatial indexes.
|
| iy |
integer |
pos.cartesian.y |
|
Zone index along y-direction, based on 7 bins. See the text on spatial indexes.
|
| iz |
integer |
pos.cartesian.y |
|
Zone index along z-direction, based on 7 bins. See the text on spatial indexes.
|
| random |
float |
|
|
A random number between 0 and 1000000. See the section on
random sampling.
|
| 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
|
| vx |
float |
phys.veloc |
km/s |
x-component of peculiar velocity
|
| vy |
float |
phys.veloc |
km/s |
y-component of peculiar velocity
|
| vz |
float |
phys.veloc |
km/s |
z-component of peculiar velocity
|
The FoFSubhalo table specifies the parent FoFHalo for each
subhalo. It may be used to determine which subhalos belong to
each FoFHalo. The SubhaloID column corresponds to the subHaloID
column in the MHalo and Subhalo tables, so additional information
about a subhalo may be obtained by finding the entry in the MHalo
table such that MHalo.subHaloID = FoFSubhalo.SubhaloID.
