Dark Matter Halo Properties vs. Local Density and Cosmic Web Location
  We study the effects of the local environmental density and the cosmic web
environment (filaments, walls, and voids) on key properties of dark matter
halos using the Bolshoi-Planck LCDM cosmological simulation. The z = 0
simulation is analysed into filaments, walls, and voids using the SpineWeb
method and also the VIDE package of tools, both of which use the watershed
transform. The key halo properties that we study are the specific mass
accretion rate, spin parameter, concentration, prolateness, scale factor of the
last major merger, and scale factor when the halo had half of its z = 0 mass.
For all these properties, we find that there is no discernible difference
between the halo properties in filaments, walls, or voids when compared at the
same environmental density. As a result, we conclude that environmental density
is the core attribute that affects these properties. This conclusion is in line
with recent findings that properties of galaxies in redshift surveys are
independent of their cosmic web environment at the same environmental density
at z ~ 0. We also find that the local web environment of the Milky Way and the
Andromeda galaxies near the centre of a cosmic wall does not appear to have any
effect on the properties of these galaxies' dark matter halos except for their
orientation, although we find that it is rather rare to have such massive halos
near the centre of a relatively small cosmic wall.
