Alignment between filaments and galaxy spins from the MaNGA
  integral-field survey
  Halos and galaxies acquire their angular momentum during the collapse of
surrounding large-scale structure. This process imprints alignments between
galaxy spins and nearby filaments and sheets. Low mass halos grow by accretion
onto filaments, aligning their spins with the filaments, whereas high mass
halos grow by mergers along filaments, generating spins perpendicular to the
filament. We search for this alignment signal using filaments identified with
the "Cosmic Web Reconstruction" algorithm applied to the Sloan Digital Sky
Survey Main Galaxy Sample and galaxy spins from the MaNGA integral-field unit
survey. MaNGA produces a map of the galaxy's rotational velocity, allowing
direct measurement of the galaxy's spin direction, or unit angular momentum
vector projected onto the sky. We find no evidence for alignment between galaxy
spins and filament directions. We do find hints of a mass-dependent alignment
signal, which is in 2-3$\sigma$ tension with the mass-dependent alignment
signal in the MassiveBlack-II and Illustris hydrodynamical simulations.
However, the tension vanishes when galaxy spin is measured using the H$\alpha$
emission line velocity rather than stellar velocity. Finally, in simulations we
find that the mass-dependent transition from aligned to anti-aligned dark
matter halo spins is not necessarily present in stellar spins: we find a
stellar spin transition in Illustris but not in MassiveBlack-II, highlighting
the sensitivity of spin-filament alignments to feedback prescriptions and
subgrid physics.
