  Recent N-body simulations have shown that the assembly history of galactic
halos depend on the density of large-scale environment. It implies that the
galaxy properties like age and size of bulge may also vary with the surrounding
large-scale structures, which are characterized by the tidal shear as well as
the density. By using a sample of 15,882 well-resolved nearby galaxies from the
Tully Catalog and the real space tidal field reconstructed from the 2Mass
Redshift Survey (2MRS), we investigate the dependence of galaxy morphological
type on the shear of large-scale environment where the galaxies are embedded.
We first calculate the large scale dimensionless overdensities (d) and the
large-scale ellipticities (e) of the regions where the Tully galaxies are
located and classify the Tully galaxies according to their morphological types
and create subsamples selected at similar value of d but span different ranges
in e. We calculate the mean ellipticity, <e>, averaged over each subsample and
find a signal of variation of <e> with galaxy morphological type: For the case
of 0.5<=d<=1.0, the ellipticals are found to be preferentially located in the
regions with low ellipticity. For the case of -0.3<=d<=0.1, the latest-type
spirals are found to be preferentially located in the regions with high
ellipticity. The null hypothesis that the mean ellipticities of the regions
where the ellipticals and the latest type spirals are located are same as the
global mean ellipticity averaged over all types is rejected at 3 sigma level
when -0.3<=d<=0.1. Yet, no signal of galaxy-shear correlation is found in the
highly overdense/underdense regions. The observed trend suggests that the
formation epochs of galactic halos might be a function not only of halo mass
and large-scale density but also of large-scale shear.
