column  type  UCD  unit  description 
subHaloId 
long 
meta.id; 

The id of this subhalo based on its rank within its parent FOF halo.

fofId 
long 
meta.id; 

The id of FOF group this subhalo belongs to.

subHaloFileId 
long 
meta.id; 

Alternative id of this subhalo based on its rank within the SUBFIND result file.

snapNum 
int 
time 

The snapshot number where this subhalo was identified.
This column corresponds to the snapnum column in
the Snapshots table in the MillenniumII database.

redshift 
float 
time 

The redshift of the snapshot to which this subhalo belongs.

np 
int 
meta.number 

Number of simulation particles in this subhalo.

mass 
real 

10^{10} M_{sun}/h 
Mass of this subhalo, given by the product of the number of particles and the mass per particle.

x 
float 
pos.cartesian.x 
Mpc/h 
The Xcoordinate of the position, determined by the particle with the minimum gravitational potential, in comoving coordinates.

y 
float 
pos.cartesian.y 
Mpc/h 
The Ycoordinate of the position, determined by the particle with the minimum gravitational potential, in comoving coordinates.

z 
float 
pos.cartesian.z 
Mpc/h 
The Zcoordinate of the position, determined by the particle with the minimum gravitational potential, in comoving coordinates.

ix 
integer 
pos.cartesian.x 

Zone index along xdirection, based on 20 bins
See the text on spatial indexes.

iy 
integer 
pos.cartesian.x 

Zone index along ydirection, based on 20 bins
See the text on spatial indexes.

iz 
integer 
pos.cartesian.x 

Zone index along zdirection, based on 20 bins
See the text on spatial indexes.

phKey 
int 


The PeanoHilbert index for the position of this subhalo.

velX 
float 
phys.veloc 
km/sec 
The Xcomponent of the peculiar velocity.

velY 
float 
phys.veloc 
km/sec 
The Ycomponent of the peculiar velocity.

velZ 
float 
phys.veloc 
km/sec 
The Zcomponent of the peculiar velocity.

cmx 
float 

Mpc/h 
The Xcoordinate of the subhalo's center of mass, in comoving coordinates.

cmy 
float 

Mpc/h 
The Ycoordinate of the subhalo's center of mass, in comoving coordinates.

cmz 
float 

Mpc/h 
The Zcoordinate of the subhalo's center of mass, in comoving coordinates.

spinX 
float 
phys.veloc.ang 
(Mpc/h) (km/sec) 
The Xcomponent of the spin of the subhalo.

spinY 
float 
phys.veloc.ang 
(Mpc/h) (km/sec) 
The Ycomponent of the spin of the subhalo.

spinZ 
float 
phys.veloc.ang 
(Mpc/h) (km/sec) 
The Zcomponent of the spin of the subhalo.

halfmassRadius 
float 
phys.size.radius 
Mpc/h 
Radius containing half of the mass of the subhalo.

vDisp 
float 
phys.veloc.dispersion 
km/sec 
The 1D velocity dispersion of the subhalo, computed from all of the subhalo particles.

vMax 
float 
phys.veloc.rotat 
km/sec 
Maximum of the circular velocity curve vCirc, where
vCirc^{2}=G M(< r)/r

vMaxRad 
float 

Mpc/h 
The radius at which the circular velocity maximum vMax is attained

mostBoundID 
long 
meta.id.assoc 

The id of the most bound particle of this subhalo.
