  We study the alignments of galaxy spin axes with respect to cosmic web
filaments as a function of various properties of the galaxies and their
constituent bulges and discs. We exploit the SAMI Galaxy Survey to identify 3D
spin axes from spatially-resolved stellar kinematics and to decompose the
galaxy into the kinematic bulge and disc components. The GAMA survey is used to
reconstruct the cosmic filaments. The mass of the bulge, defined as the product
of stellar mass and bulge-to-total flux ratio M_bulge=M_star x (B/T), is the
primary parameter of correlation with spin-filament alignments: galaxies with
lower bulge masses tend to have their spins parallel to the closest filament,
while galaxies with higher bulge masses are more perpendicularly aligned.
M_star and B/T separately show correlations, but they do not fully unravel
spin-filament alignments. Other galaxy properties, such as visual morphology,
stellar age, star formation activity, kinematic parameters and local
environment, are secondary tracers. Focusing on S0 galaxies, we find
preferentially perpendicular alignments, with the signal dominated by high-mass
S0 galaxies. Studying bulge and disc spin-filament alignments separately
reveals additional information about the formation pathways of the
corresponding galaxies: bulges tend to have more perpendicular alignments,
while discs show different tendencies according to their kinematic features and
the mass of the associated bulge. The observed correlation between the flipping
of spin-filament alignments and the growth of the bulge can be explained by
mergers, which drive both alignment flips and bulge formation.
