Assembly history of subhalo populations in galactic and cluster sized
  dark haloes
  We make use of two suits of ultra high resolution N-body simulations of
individual dark matter haloes from the Phoenix and the Aquarius Projects to
investigate systematics of assembly history of subhaloes in dark matter haloes
differing by a factor of $1000$ in the halo mass. We have found that real
progenitors which built up present day subhalo population are relatively more
abundant for high mass haloes, in contrast to previous studies claiming a
universal form independent of the host halo mass. That is mainly because of
repeated counting of the 're-accreted' (progenitors passed through and were
later re-accreted to the host more than once) and inclusion of the 'ejected'
progenitor population(progenitors were accreted to the host in the past but no
longer members at present day) in previous studies. The typical accretion time
for all progenitors vary strongly with the host halo mass, which is typical
about $z \sim 5$ for the galactic Aquarius and about $z \sim 3$ for the cluster
sized Phoenix haloes. Once these progenitors start to orbit their parent
haloes, they rapidly lose their original mass but not their identifiers, more
than $55$ ($50$) percent of them survive to present day for the
Phoenix(Aquarius) haloes. At given redshift, survival fraction of the accreted
subhalo is independent of the parent halo mass, whilst the mass-loss of the
subhalo is more efficient in high mass haloes. These systematics results in
similarity and difference in the subhalo population in dark matter haloes of
different masses at present day.
