3.3.19.4  :  SubHalo

The table stores all the subhalos identified with the SUBFIND algorithm in the friends-of-friends groups identified within the Millennium-II Simulation of the FOF groups themselves are stored in the FOF table.

columntypeUCDunitdescription
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 Millennium-II 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 1010 Msun/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 X-coordinate of the position, determined by the particle with the minimum gravitational potential, in comoving coordinates.
y float pos.cartesian.y Mpc/h The Y-coordinate of the position, determined by the particle with the minimum gravitational potential, in comoving coordinates.
z float pos.cartesian.z Mpc/h The Z-coordinate of the position, determined by the particle with the minimum gravitational potential, in comoving coordinates.
ix integer pos.cartesian.x Zone index along x-direction, based on 20 bins
See the text on spatial indexes.
iy integer pos.cartesian.x Zone index along y-direction, based on 20 bins
See the text on spatial indexes.
iz integer pos.cartesian.x Zone index along z-direction, based on 20 bins
See the text on spatial indexes.
phKey int The Peano-Hilbert index for the position of this subhalo.
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.
cmx float Mpc/h The X-coordinate of the subhalo's center of mass, in comoving coordinates.
cmy float Mpc/h The Y-coordinate of the subhalo's center of mass, in comoving coordinates.
cmz float Mpc/h The Z-coordinate of the subhalo's center of mass, in comoving coordinates.
spinX float phys.veloc.ang (Mpc/h) (km/sec) The X-component of the spin of the subhalo.
spinY float phys.veloc.ang (Mpc/h) (km/sec) The Y-component of the spin of the subhalo.
spinZ float phys.veloc.ang (Mpc/h) (km/sec) The Z-component 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 1-D 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
vCirc2=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.