Integrated accretion disc angular momentum removal and astrophysical jet acceleration mechanism

• Published in: Monthly notices of the Royal Astronomical Society Vol. 458; no. 4; pp. 4400 - 4421
• Main Author: Bellan, P. M.
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 01.06.2016
• Subjects: Acceleration; Accretion disks; Angular momentum; Astrophysics; Electric current; Electric currents; Electric fields; Electric power; Fluids; Ions; Nanoparticles; Spirals; accretion, accretion discs
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stw562

Ions and neutrals in the weakly ionized plasma of an accretion disc are tightly bound because of the high ion–neutral collision frequency. A cluster of a statistically large number of ions and neutrals behaves as a fluid element having the charge of the ions and the mass of the neutrals. This fluid element is effectively a metaparticle having such an extremely small charge-to-mass ratio that its cyclotron frequency can be of the order of the Kepler angular frequency. In this case, metaparticles with a critical charge-to-mass ratio can have zero canonical angular momentum. Zero canonical angular momentum metaparticles experience no centrifugal force and spiral inwards towards the central body. Accumulation of these inward spiralling metaparticles near the central body produces radially and axially outward electric fields. The axially outward electric field drives an out-of-plane poloidal electric current along arched poloidal flux surfaces in the highly ionized volume outside the disc. This out-of-plane current and its associated magnetic field produce forces that drive bidirectional astrophysical jets flowing normal to and away from the disc. The poloidal electric current circuit removes angular momentum from the accreting mass and deposits this removed angular momentum at near infinite radius in the disc plane. The disc region is an electric power source ( $\boldsymbol {E}\cdot \boldsymbol {J} <0$ ) while the jet region is an electric power sink ( $\boldsymbol {E}\cdot \boldsymbol {J}>0$ ).