The power of relativistic jets is larger than the luminosity of their accretion disks

TLDR: An analysis of archival observations of a sample of blazars (quasars whose jets point towards Earth) that overcomes previous limitations finds a clear correlation between jet power, as measured through the γ-ray luminosity, and accretion luminosity; this implies that the magnetic field threading the black hole horizon reaches the maximum value sustainable by the accreting matter.

Abstract: Blazars are quasars with a jet pointing towards Earth; analysis of archival observations of a sample of blazars reveals that jet power is larger than, and correlates with, the accretion luminosity, in agreement with numerical simulations. An analysis of archival observations of a sample of blazars — quasars whose jets point towards Earth — shows a clear correlation between the power of the relativistic jets produced from these active galactic nuclei measured as γ-ray luminosity and the accretion luminosity as measured by the broad emission lines. In agreement with numerical simulations, jet power dominates over the disk luminosity, which suggests that the rotational energy of spinning black holes powers these jets and that the magnetic field is a catalyst for this process. Theoretical models for the production of relativistic jets from active galactic nuclei predict that jet power arises from the spin and mass of the central supermassive black hole, as well as from the magnetic field near the event horizon1. The physical mechanism underlying the contribution from the magnetic field is the torque exerted on the rotating black hole by the field amplified by the accreting material. If the squared magnetic field is proportional to the accretion rate, then there will be a correlation between jet power and accretion luminosity. There is evidence for such a correlation2,3,4,5,6,7,8, but inadequate knowledge of the accretion luminosity of the limited and inhomogeneous samples used prevented a firm conclusion. Here we report an analysis of archival observations of a sample of blazars (quasars whose jets point towards Earth) that overcomes previous limitations. We find a clear correlation between jet power, as measured through the γ-ray luminosity, and accretion luminosity, as measured by the broad emission lines, with the jet power dominating the disk luminosity, in agreement with numerical simulations9. This implies that the magnetic field threading the black hole horizon reaches the maximum value sustainable by the accreting matter10.