Vol 11, No 11 (2011) / Foschini

Accretion and jet power in active galactic nuclei

Luigi Foschini


The classical diagrams of radio loudness and jet power as a function of mass and accretion rate of the central spacetime singularity in active galactic nuclei are reanalyzed by including the data of the recently discovered powerful relativistic jets in Narrow-Line Seyfert 1 Galaxies. The results are studied in the light of the known theories of relativistic jets, indicating that, although the Blandford-Znajek mechanism is sufficient to explain the power radiated by BL Lac Objects, it fails to completely account for the power from quasars and Narrow-Line Seyfert 1 Galaxies. This favors the scenario outlined by Cavaliere & D’Elia of a composite jet, with a magnetospheric core plus a hydromagnetic component emerging when the accretion power increases and the disk becomes radiation-pressure dominated. A comparison with Galactic compact objects is also made, finding some striking similarities, indicating that since neutron stars are low-mass jet systems analogous to black holes, Narrow-Line Seyfert 1 Galaxies are low-mass counterparts of blazars.


galaxies: jets — BL Lacertae objects: general — quasars: general — galaxies: Seyfert

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