Linear Tidal Vestige found in the WM Sheet
  We present a vestige of the linear tidal influence on the spin orientations
of the constituent galaxies of the WM sheet discovered in the vicinity of the
Virgo cluster and the Local Void. The WM sheet is chosen as an optimal target
since it has a rectangular parallelepiped-like shape whose three sides are in
parallel with the supergalactic Cartesian axes. Determining three probability
density functions of the absolute values of the supergalactic Cartesian
components of the spin vectors of the WM sheet galaxies, we investigate their
alignments with the principal directions of the surrounding large-scale tidal
field. When the WM sheet galaxies located in the central region within the
distance of $2\,h^{-1}$Mpc are excluded, the spin vectors of the remaining WM
sheet galaxies are found to be weakly aligned, strongly aligned, and strongly
anti-aligned with the minor, intermediate and major principal directions of the
surrounding large-scale tidal field, respectively. To examine whether or not
the origin of the observed alignment tendency from the WM sheet is the linear
tidal effect, we infer the eigenvalues of the linear tidal tensor from the
axial ratios of the WM sheet with the help of the Zel'dovich approximation and
conduct a full analytic evaluation of the prediction of the linear tidal torque
model for the three probability density functions. A detailed comparison
between the analytical and the observational results reveals a good
quantitative agreement not only in the behaviors but also in the amplitudes of
the three probability density functions.
