Blandford Payne Trial

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The Blandford-Payne process , named after the astrophysicists RD Blandford and DG Payne, who proposed the effect in 1982, describes how magnetic processes in an accretion flow can lead to an outflow of matter.

Accretion fluxes near compact objects are very hot, typically on the order of several 10 6 K and more, so the incident material is ionized and forms a plasma . This accretion plasma consists mainly of ions and electrons . The result is that the moving electrical charges induce magnetic fields . As a result, the accretion flux is penetrated by magnetic field lines and typically forms the configuration of a rotating magnetized accretion disk . Since the magnetic field lines are coupled to the plasma, a large number of magnetic field lines also rotate with the disk, which are collectively referred to as the magnetosphere .

This magnetic field pulls plasma particles out of the surface of the accretion disk, a process known by astrophysicists as disk wind. Typical outflow velocities are comparable to the Kepler velocity at the respective disk radius. The speed of the disk wind increases as the radii become smaller and can reach relativistic speeds (v jet = 0.995 c ) if the disk rotates very close to a black hole .

The rotating accretion disk with its magnetic pressure creates a disk wind that causes centrifugally driven outflows. In contrast, there is the Blandford-Znajek process , which extracts the rotational energy of rotating black holes. For the Blandford-Payne process, only a rotating, magnetized plasma is required, as z. B. in protostars , T-Tauri stars and Herbig-Ae / Be stars , Herbig-Haro objects or interacting binary star systems as well as symbiotic stars , X-ray binary stars and cataclysmic variables .

Blandford-Payne process and Blandford-Znajek process are two mechanisms that are discussed as the cause of the generation of jets in Active Galactic Nuclei (AGN) and X-ray binary stars with black holes (BHXBs) . When the disk wind is bundled by magnetic Lorentz forces or by the radiation pressure of hot ambient sources, a directed ( collimated ) gas flow results , the so-called jet.

It may soon be possible to use high-resolution VLBI observations to clarify which mechanism is working in the respective jet source. Intercontinental interferometry (VLBI) in the millimeter range already achieves spatial resolutions of a few to a few tens of Schwarzschild radii in AGN such as B. M87 . The structures at the jet base would give away the mechanism because the Blandford-Znajek process creates a narrow starting point for the jet, whereas the Blandford-Payne scenario would have a wide jet base on the order of several hundred gravitational radii .

Individual evidence

  1. ↑ Blandford, RD; Payne, DG: Hydromagnetic flows from accretion discs and the production of radio jets . In: Monthly Notices of the Royal Astronomical Society, vol. 199, June 1982, p. 883-903. . June 6, 1982. bibcode : 1982MNRAS.199..883B . doi : 10.1103 / PhysRevLett.120.061301 .
  2. ↑ a b c Blandford-Payne scenario. In: Lexicon of Astrophysics. Andreas Müller (astronomer) , accessed on September 20, 2019 .
  3. ↑ Begelman, et al .: Evidence for Black Holes . In: Science, Volume 300, Issue 5627, pp. 1898-1904 (2003). . June 2003. bibcode : 2003Sci ... 300.1898B . doi : 10.1126 / science.1085334 .
  4. ↑ L. Hartmann: Accretion Processes in Star Formation (Cambridge Astrophysics) . Cambridge University Press, Cambridge 2008, ISBN 978-0-521-53199-3 .
  5. ↑ SN Shore, M. Livio, EPJ van den Heuvel, Astrid Orr, H. Nussbaumer: Interacting Binaries: Saas-Fee Advanced Course 22nd Lecture Notes 1992. Swiss Society for Astrophysics and Astronomy (Saas-Fee Advanced Courses) . Springer Verlag, Berlin 1993, ISBN 978-3-540-57014-1 .
  6. ^ Krichbaum et al .: VLBI at the highest frequencies - AGN studied with micro-arcsecond resolution . In: Proceedings of the 8th European VLBI Network Symposium. September 26-29, 2006, Torun, Poland. . November 9, 2006. arxiv : astro-ph / 0611288 . bibcode : 2006evn..confE ... 2K .