Warping Away Gravitational Instabilities in Protoplanetary Discs

Abstract

We perform three-dimensional smoothed-particle hydrodynamics simulations of warped, non-coplanar gravitationally unstable discs to show that as the warp propagates through the self-gravitating disk, it heats up the disk rendering it gravitationally stable, thus losing their spiral structure and appearing completely axisymmetric. In their youth, protoplanetary discs are expected to be massive and self-gravitating, which results in nonaxisymmetric spiral structures. However recent observations of young protoplanetary discs with the Atacama Large Millimeter/submillimeter Array have revealed that discs with large-scale spiral structure are rarely observed in the midplane. Instead, axisymmetric discs, with some also having ring and gap structures, are more commonly observed. Our work invloving warps, non-coplanar disk structures that are expected to commonly occur in young discs, potentially resolves this discrepancy between observations and theoretical predictions. We demonstrate that they are able to suppress the large-scale spiral structure of self-gravitating protoplanetary discs.