Tidal disruptions of white dwarfs as probes for intermediate mass black holes in globular clusters

• Applicant: Professor Dr. Stephan Rosswog
• Subject Area: Astrophysics and Astronomy
• Term: from 2008 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 67273889

Suggestive evidence has accumulated that intermediate mass black holes (IMBHs) exist in some globular clusters. As stars diffuse in the cluster, some will inevitably wander sufficiently close to the hole that they suffer a tidal disruption. An attractive feature of the IMBH hypothesis is its potential to disrupt not only solar-type stars but also compact white dwarf stars. We have recently investigated the fate of white dwarfs that approach the hole close enough to be disrupted and compressed to such an extent that explosive nuclear burning is triggered. We found that thermonuclear ignition is a natural outcome for white dwarfs of all masses passing well within the tidal radius. A peculiar, underluminous thermonuclear explosion accompanied by a soft X-ray transient signal would, if detected, be a compelling testimony for the presence of an IMBH.These previous calculations were based on the use of a relativistic pseudo-potential. In this proposal we suggest to explore the disruption process in a relativistic approach on a fixed black hole background metric. The specific goal is to implement relativistic gravity and hydrodynamics into the current hydrodynamics plus nuclear network model. Using this tool we will study particularly close encounters where strong gravity effects are important, both with rotating and non-rotating black holes.

• DFG Programme: Research Grants