Dynamically important magnetic fields near accreting supermassive black holes


Accreting supermassive black holes at the centres of active galaxies often produce ‘jets’—collimated bipolar outflows of relativistic particles1. Magnetic fields probably play a critical role in jet formation2,3 and in accretion disk physics4. A dynamically important magnetic field was recently found near the Galactic Centre black hole5. If this is common and if the field continues to near the black hole event horizon, disk structures will be affected, invalidating assumptions made in standard models3,6,7. Here we report that jet magnetic field and accretion disk luminosity are tightly correlated over seven orders of magnitude for a sample of 76 radio-loud active galaxies. We conclude that the jet-launching regions of these radio-loud galaxies are threaded by dynamically important fields, which will affect the disk properties. These fields obstruct gas infall, compress the accretion disk vertically, slow down the disk rotation by carrying away its angular momentum in an outflow3 and determine the directionality of jets8.

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Figure 1: Diagram of an AGN jet.
Figure 2: Measured magnetic flux of the jet, Φjet, versus .


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We thank A. Lobanov, M. Sikora and J. McKinney for discussions and N. Sabha for comments on the manuscript. M.Z. was supported by the German Deutsche Forschungsgemeinschaft, DFG, via grant SFB 956 project A2. A.T. was supported by a Princeton Center for Theoretical Science fellowship and by NASA through the Einstein fellowship program, grant PF3-140115.

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M.Z. proposed the experiment, compiled the data and performed most of the analysis. E.C.-B. wrote most of the main text and contributed to the theoretical analysis and implications of the work. T.S. contributed to the analysis and discussion of the data, and A.T. contributed to the theoretical analysis and implications of the work. All authors contributed ideas, discussed the results and wrote the manuscript.

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Correspondence to M. Zamaninasab.

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Extended data figures and tables

Extended Data Table 1 Blazar sample
Extended Data Table 2 Radio galaxy sample
Extended Data Table 3 Partial correlation analysis results based on cens_tau algorithm
Extended Data Table 4 Results of partial correlation analysis based on ppcorr algorithm

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Zamaninasab, M., Clausen-Brown, E., Savolainen, T. et al. Dynamically important magnetic fields near accreting supermassive black holes. Nature 510, 126–128 (2014). https://doi.org/10.1038/nature13399

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