Collaborative Research: Tidal Disruption of Stars by Massive Black Holes

The disruption and accretion of stars by super-massive black holes (SMBHs) has been linked to tens of luminous flares observed in the nuclei of nearby galaxies. Our theo- retical understanding of these tidal disruption events (TDEs), however, remains incomplete. The authors propose a collaborative effort that brings together experts in hydrodynamics, general relatively and radiative transfer to fill in several important theoretical gaps in our understanding of TDEs. This understanding requires a multi-pronged approach that attempts to resolve the underlying physics at a wide range of scales. Additionally, the effects of the star’s properties, the parameters of its orbit and the spacetime distortions induced by the SMBH have only recently been considered. Fully 3D simulations of accretion disks are expensive, and as a result there is trade-off between running a simulation with significant resolution that only resolves a fraction of the disk and global simulations at moderate resolution that resolve the full structure. For TDEs the trade-offs are even more pronounced and require a large range of scales to be resolved simultaneously. As a consequence, a single simulation of the full problem incorporating all of the aforementioned effects would not only be prohibitively expensive, but also difficult to interpret because of the complexity of the interplay between the various physical mechanisms at different scales. Instead, we propose to answer these questions via a series of numerical experiments that isolate the key processes that regulate the disruption itself, the formation of the debris disk, the production of jets and the generation of the emanating radiation. In addition to being computationally feasible, this approach will enable a thorough understanding of each of the processes, which are likely highly reminiscent of the well-studied phenomenology of steadily-accreting AGN.