# 28th Texas Symposium on Relativistic Astrophysics

13-18 December 2015
International Conference Centre Geneva
Europe/Zurich timezone

## Black Hole Jets from MRI-Generated Magnetic Fields

16 Dec 2015, 16:15
21m
Level 0, Room 23 (International Conference Centre Geneva)

### Level 0, Room 23

#### International Conference Centre Geneva

17 Rue de Varembé, 1211 Geneva

### Speaker

Dr Kyle Parfrey (Lawrence Berkeley National Laboratory)

### Description

We propose a scenario for launching relativistic jets from rotating black holes, in which small-scale magnetic flux loops, sustained by disc turbulence, are forced to inflate and open by differential rotation between the black hole and the accretion flow. This mechanism does not require a large-scale net magnetic flux in the accreting plasma, whose presence in the environment of the central engine is questionable in many jet sources. Estimates suggest that the process could operate effectively for a wide range of systems, and particularly naturally and efficiently when the accretion flow is retrograde. We present the results of general-relativistic force-free electrodynamic simulations demonstrating the time evolution of the black hole's magnetosphere, the cyclic formation of jets, and the effect of magnetic reconnection. The jets are highly variable on timescales $\sim 10$-$10^3\, r_{\rm g}/c$, where $r_{\rm g}$ is the black hole's gravitational radius. The reconnecting current sheets observed in the simulations may be responsible for the hard X-ray emission from accreting black holes.

### Primary author

Dr Kyle Parfrey (Lawrence Berkeley National Laboratory)

### Co-authors

Prof. Andrei Beloborodov (Columbia University) Prof. Dimitrios Giannios (Purdue University)

### Presentation Materials

 14_1615_Parfrey_BlackHole_Jets.key 14_1615_Parfrey_BlackHole_Jets.pdf