The orientation of galaxy pairs with filamentary structures: dependence
  on morphology
  Aims. With the aim of performing an analysis of the orientations of galaxy
pair systems with respect to the underlying large-scale structure, we study the
alignment between the axis connecting the pair galaxies and the host cosmic
filament where the pair resides. In addition, we analyze the dependence of the
amplitude of the alignment on the morphology of pair members as well as
filament properties. Methods. We build a galaxy pair catalog requiring $r_p <
100\kpc$ and $\Delta V < 500 \kms $ within redshift $z<0.1$ from the Sloan
Digital Sky Survey (SDSS). We divided the galaxy pair catalog taking into
account the morphological classification by defining three pair categories
composed by elliptical-elliptical (E-E), elliptical-spiral (E-S) and
spiral-spiral (S-S) galaxies. We use a previously defined catalog of filaments
obtained from SDSS and we select pairs located closer than $1\mpc$ from the
filament spine, which are considered as members of filaments. For these pairs,
we calculate the relative angle between the axis connecting each galaxy, and
the direction defined by the spine of the parent filament.
  Results. We find a statistically significant alignment signal between the
pair axes and the spine of the host filaments consistent with a relative excess
of $ \sim$ 15\% aligned pairs. We obtain that pairs composed by elliptical
galaxies exhibit a stronger alignment, showing a higher alignment signal for
pairs closer than 200 $\kpc$ to the filament spine. In addition, we find that
the aligned pairs are associated with luminous host filaments populated with a
high fraction of elliptical galaxies.
  The findings of this work show that large scale structures play a fundamental
role in driving galactic anisotropic accretion as induced by galaxy pairs
exhibiting a preferred alignment along the filament direction.
