Warped Disk Galaxies. I. Linking U type Warps in Groups/Clusters to Jellyfish Galaxies

TL;DR

This study links U-shaped warped disk galaxies in groups and clusters to ram pressure stripping, suggesting a non-tidal environmental mechanism for their formation, supported by observational data and simulations.

Contribution

It proposes that ram pressure stripping, rather than tidal interactions, can explain U-type warps in galaxies within groups and clusters, a novel insight supported by extensive data and simulations.

Findings

U-types are more common in groups/clusters than in fields.

U-types have properties similar to jellyfish galaxies caused by ram pressure stripping.

Most RPS galaxies in simulations show U-shaped stellar warps.

Abstract

arped disk galaxies are classified into two morphologies: S- and U-types. Conventional theories routinely attribute both types to galactic tidal interaction and/or gas accretion, but reproducing of U-types in simulations is extremely challenging. Here we investigate whether both types are governed by the same mechanisms using the most extensive sample of $\sim$8000 nearby (0.02\,$<$\,z\,$<$\,0.06) massive ($M_{*}/M_{\odot}$\,$>$\,$10^9$) edge-on disks from SDSS. We find that U-types show on average bluer optical colors and higher specific star formation rate (sSFR) than S-types, with more strongly warped U-types having higher sSFR. We also find that while the S-type warp properties correlate with the tidal force by the nearest neighbor regardless of the environment, there is no such correlation for U-types in groups/clusters, suggesting a non-tidal environmental could be at play for U-types, such as ram pressure stripping (RPS). Indeed, U-types are more common in groups/clusters than in fields and they have stellar mass, gas fraction, sSFR enhancement and phase-space distribution closely analogous to RPS-induced jellyfish galaxies in clusters. We furthermore show that the stellar disks of most RPS galaxies in the IllustirsTNG simulation are warped in U-shape and bent in opposite direction of stripped gas tails, satisfying theoretical expectations for stellar warps embeded in jellyfishes. We therefore suggest that despite the majority of U-types that live in fields being still less explained, RPS can be an alternative origin for those in groups/clusters.