The alignment of satellite galaxies and cosmic filaments: observations
  and simulations
  The accretion of satellites onto central galaxies along vast cosmic filaments
is an apparent outcome of the anisotropic collapse of structure in our
Universe. Numerical work (based on gravitational dynamics of N-body
simulations) indicates that satellites are beamed towards hosts along preferred
directions imprinted by the velocity shear field. Here we use the Sloan Digital
Sky Survey to observationally test this claim. We construct 3D filaments and
sheets and examine the relative position of satellite galaxies. A statistically
significant alignment between satellite galaxy position and filament axis in
observations is confirmed. We find a qualitatively compatible alignments by
examining satellites and filaments similarly identified in the Millennium
simulation, semi-analytical galaxy catalogue. We also examine the dependence of
the alignment strength on galaxy properties such as colour, magnitude and
(relative) satellite magnitude, finding that the alignment is strongest for the
reddest and brightest central and satellite galaxies. Our results confirm the
theoretical picture and the role of the cosmic web in satellite accretion.
Furthermore our results suggest that filaments identified on larger scales can
be reflected in the positions of satellite galaxies that are quite close to
their hosts.
