The impact of filamentary accretion of subhaloes on the shape and
  orientation of haloes
  Dark matter haloes are formed through hierarchical mergers of smaller haloes
in large-scale cosmic environments, and thus anisotropic subhalo accretion
through cosmic filaments have some impacts on halo structures. Recent studies
using cosmological simulations have shown that the orientations of haloes
correlate with the direction of cosmic filaments, and these correlations
significantly depend on the halo mass. Using high-resolution cosmological
$N$-body simulations, we quantified the strength of filamentary subhalo
accretion for galaxy- and group-sized host haloes ($M_{\rm
host}=5\times10^{11-13}M_{\odot}$) by regarding the entry points of subhaloes
as filaments and present statistical studies that how the shape and orientation
of host haloes at redshift zero correlate with the strength of filamentary
subhalo accretion. We confirm previous studies that found the host halo mass
dependence of the alignment between orientations of haloes and filaments. We
also show that, for the first time, the shape and orientation of haloes weakly
correlate with the strength of filamentary subhalo accretion even if the host
halo masses are the same. Minor-to-major axis ratios of haloes tend to decrease
as their filamentary accretion gets stronger. Haloes with highly anisotropic
accretion become more spherical or oblate, while haloes with isotropic
accretion become more prolate or triaxial. For haloes with strong filamentary
accretion, their major axes are preferentially aligned with the filaments,
while their angular momentum vectors tend to be slightly more misaligned.
