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Colloquium by Ramesh Narayn (Harvard)

Black Hole Spin and Relativistic Jets

Abstract:  Black holes are very exotic objects. At the same time, they are also amazingly simple. An astrophysical black hole is believed to be fully described with just two parameters: mass and spin. A major goal of current research is to relate observational manifestations of black holes to these two intrinsic parameters. Relativistic jets, which are often associated with accreting black holes, e.g., in active  galactic nuclei, black hole X-ray binaries, gamma-ray bursts and tidal disruption events, are particularly interesting in this context. Astrophysicists have for long speculated that black hole spin energy might be the energy source behind jets. Two recent advances have strengthened the case. First, numerical general relativistic magnetohydrodynamic simulations of accreting spinning black holes show relativistic jets forming spontaneously. In at least some cases, there is unambiguous evidence that much of the jet energy comes from the black hole, not the disk. Second, spin parameters of a number of accreting stellar-mass black holes have been measured. For  ballistic jets from these systems, the radio luminosity of the jet appears to correlate with the spin of the black hole. Although the evidence is still marginal, if verified, it would strongly suggest a causal relationship between black hole spin and jet power.

Time: Jun. 10, 2015, 2:30 pm

Venue: A601, NAOC