title: The power of relativistic jets is larger than the luminosity of their accretion disks.
abstract: 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 horizon. 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 correlation, 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 simulations. This implies that the magnetic field threading the black hole horizon reaches the maximum value sustainable by the accreting matter.
authors.affiliation: Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Ghisellini
authors.affiliation: Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Tavecchio
authors.affiliation: 1] Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate, Italy [2] Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Brera, Via E. Brera 28, I-20121 Milano, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Maraschi
authors.affiliation: 1] Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate, Italy [2] Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, I-34135 Trieste, Italy [3] Istituto Nazionale di Fisica Nucleare - Sezione di Trieste, Via Valerio 2, I-34127 Trieste, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Celotti
authors.affiliation: 1] Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate, Italy [2] Università dell'Insubria, Dipartimento di Fisica e Matematica, Via Valleggio 11, I-22100 Como, Italy [3] European Southern Observatory, Karl-Schwarzschild-Strasse 2, 8578 Garching bei München, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Sbarrato