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There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
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Low-luminosity GRBs or X-ray flashes (XRFs), which often accompany supernovae, are typically ascribed to either the supernova shock breakout or weak GRBs powered by the central engine of stellar mass. We propose the tidal disruption of a white dwarf (WD) by an intermediate-mass black hole (IMBH) as another channel for XRFs. Such disruptions last for 100-5000 seconds. The release of gravitational energy over short time generates a powerful flare. The magnetic field is quickly amplified in the fallback material, and then the BH launches a slow uncollimated jet. The emission from jet photosphere dominates X-rays with Comptonized thermal spectrum, while the expanding jet shell produces most of IR/optical. The prompt flare may be followed by an underluminous fast supernova, resulting from a tidal compression and thermonuclear ignition of a WD. High event rate in dwarf galaxies warrants searches among the known and future transients observed with Swift satellite.
We perform detailed dynamical and spectral modeling of a candidate disruption source GRB060218/SN2006aj. The BH mass is independently estimated to be 20,000 solar masses based on (1) the event duration, (2) the jet base radius from the thermal X-ray component, and (3) the properties of a host galaxy. The supernova position is consistent with a center of a dwarf host galaxy. Other potential candidates are the flashes with very weak/absent supernovae such as XRF040701."
