Tidally induced warps of spiral galaxies in IllustrisTNG
  Warps are common features in both stellar and gaseous disks of nearby spiral
galaxies with the latter usually easier to detect. Several theories have been
proposed in the literature to explain their formation and prevalence, including
tidal interactions with external galaxies. Observational correlations also
suggest the importance of tides for warp formation. Here, we use the TNG100 run
from the magnetohydrodynamical cosmological simulation suite IllustrisTNG to
investigate the connection between interactions and the formation of gas warps.
We find that in the sample of well-resolved gas-rich spiral galaxies
($10^{10}\lesssim\mathrm{M_{*}/M_{\odot}}\lesssim10^{11}$ at $z=0$) from the
simulation TNG100-1, about $16\%$ possess the characteristic S-shaped warp.
Around one third of these objects have their vertical morphology induced by
interactions with other galaxies. Half of these interactions end with the
perturber absorbed by the host. Warps formed in interactions are more
asymmetrical than the remaining sample, however after the interaction the
asymmetry decreases with time. We find that warps induced by interactions
survive on average for $<1$ Gyr. The angle between the orbital angular momentum
of the perturber and the angular momentum of the host's disk that most likely
leads to warp formation is around 45 degrees. While our main goal is to
investigate tidally induced warps, we find that during interactions in addition
to tides, new gas that is accreted from infalling satellites also can
contribute to warp formation.
