Colloq Abstract - Metzger

April 8

11am Mountain

 

Brian Metzger

Columbia University

 

A Zoo of Tidal Disruption Flares

Occasionally a star in a galactic nucleus is perturbed onto a highly eccentric orbit that brings it close enough to the central supermassive black hole to be torn apart by tidal forces.  Rapid accretion of stellar debris following such a tidal disruption event (TDE) has long been predicted to power a luminous electromagnetic flare, detectable to cosmological distances.  I will review the basic theory of TDEs and recent observations of TDE flares.  I will describe a simplified model for their thermal (optical, soft X-ray) emission based on outflows from the accretion disk reprocessing harder emission from the inner disk.  A small fraction of TDEs are observed to produce relativistic jets and bright non-thermal radio emission.  I will describe relativistic hydrodynamical simulations of the deceleration of the prototypical TDE jets Swift J1644+57, which point to a complex jet angular structure.  I will briefly assess the prospects for upcoming GHz radio surveys, such as the VLASS, to detect and characterize TDE jets.  Finally, I will highlight several TDE “rate crises”, namely that the total predicted TDE rate observed thermal flare rate jetted TDE rate.

 

 

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