Relativistic jet

Relativistic jet

__NOTOC__:"The lower-energy non-relativistic version of this phenomenon is described at polar jet."

Relativistic jets are extremely powerful jets of plasma which emerge from the centers of some active galaxies, notably radio galaxies and quasars. Their lengths can reach several thousand [Biretta, J. (1999, January 6). Hubble Detects Faster-Than-Light Motion in Galaxy M87 (http://www.stsci.edu/ftp/science/m87/m87.html)] or even hundreds of thousands of light years. [Yale University - Office of Public Affairs (2006, June 20). Evidence for Ultra-Energetic Particles in Jet from Black Hole (http://www.yale.edu/opa/newsr/06-06-20-01.all.html)] It is believed that the twisting of magnetic fields in the accretion disk collimates the outflow along the rotation axis of the central object, so that when conditions are suitable, a jet will emerge from each face of the accretion disk. If the jet is oriented along the line of sight to earth, relativistic beaming will change its apparent brightness. The mechanisms for the creation of jets [Meier, L. M. (2003). The Theory and Simulation of Relativistic Jet Formation: Towards a Unified Model For Micro- and Macroquasars, 2003, "New Astron. Rev. ", 47, 667. (http://arxiv.org/abs/astro-ph/0312048)] and the composition of jets [ Georganopoulos, M.; Kazanas, D.; Perlman, E.; Stecker, F. (2005) Bulk Comptonization of the Cosmic Microwave Background by Extragalactic Jets as a Probe of their Matter Content, "The Astrophysical Journal ", 625, 656. (http://arxiv.org/abs/astro-ph/0502201)] are still a matter of much debate in the scientific community. It is believed that the jets are composed of an electrically neutral mixture of electrons, positrons and protons in some proportion.

Similar jets, though on a much smaller scale, can develop around the accretion disks of neutron stars and stellar black holes. These systems are often called microquasars. A famous example is SS433, whose well-observed jet has a velocity of 0.23c, although other microquasars appear to have much higher (but less well measured) jet velocities. Even weaker and less-relativistic jets may be associated with many binary systems; the acceleration mechanism for these jets may be similar to the magnetic reconnection processes observed in the Earth's magnetosphere and the solar wind.

It is believed that the formation of relativistic jets is the key to explaining the production of gamma-ray bursts. These jets have Lorentz factors of ~ 100, making them one of the fastest celestial objects currently known.

Rotating black hole as energy source

Because of the enormous amount of energy needed to launch a relativistic jet, some jets are thought to be powered by spinning black holes. There are two competing theories for how the energy is transferred from the black hole to the jet.
* "Blandford-Znajek process". [Blandford, R. D., Znajek, R. L. (1977), "Monthly Notices of the Royal Astronomical Society", 179, 433] This is the most commonly agreed theory for the extraction of energy from the central black hole. The magnetic fields around the accretion disk are dragged by the spin of the black hole. The relativistic material is possibly launched by the tightening of the field lines.
* "Penrose mechanism". [Penrose, R. (1969). Gravitational collapse: The role of general relativity. "Nuovo Cimento Rivista", Numero Speciale 1, 252-276.] This extracts energy from a rotating black hole by frame dragging. This theory was later proven to be able to extract relativistic particle energy, [Williams, R. K. (1995, May 15). Extracting x rays, Ύ rays, and relativistic e-e+ pairs from supermassive Kerr black holes using the Penrose mechanism. "Physical Review", 51(10), 5387-5427.] and subsequently shown to be a possible mechanism for the formation of jets. [Williams, R. K. (2004, August 20). Collimated escaping vortical polar e-e+ jets intrinsically produced by rotating black holes and Penrose processes. "The Astrophysical Journal", 611, 952-963. (http://arxiv.org/abs/astro-ph/0404135)]

Other images



ee also

*Bipolar outflow

Further reading

*Melia, Fulvio, "The Edge of Infinity. Supermassive Black Holes in the Universe" 2003, Cambridge University Press, ISBN 978-0-521-81405-8 (Cloth)

References


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Jet — may refer to:Aerospace*Jet engine *Jet aircraft *Jet Airways, an airline based in India serving domestic and international routes *JetLite, subsidiary of Jet Airways *JetBlue Airways, an airline based in New York *Jetstar Airways, an Australian… …   Wikipedia

  • Relativistic beaming — Doppler beaming redirects here. For other uses named for Christian Doppler, see Doppler (disambiguation). Only a single jet is visible in M87. Two jets are visib …   Wikipedia

  • Relativistic particle — A relativistic particle is a particle which moves with a relativistic speed; that is, a speed comparable to the speed of light. This is achieved by photons to the extent that effects described by special relativity are able to describe those of… …   Wikipedia

  • Relativistic speed — A Relativistic speed is a speed which is a significant proportion of the speed of light. Therefore scientific analysis must take the consequences of special relativity into account. A relativistic particle is a subatomic particle moving at… …   Wikipedia

  • Relativistic Heavy Ion Collider — Hadron colliders Caption=The Relativistic Heavy Ion Collider at Brookhaven National Laboratory. Some of the superconducting magnets were manufactured by Northrop Grumman Corp. at Bethpage, New York. Note especially the second, independent ring… …   Wikipedia

  • Relativistic rocket — A relativistic rocket is any spacecraft that is travelling at a velocity close enough to light speed for relativistic effects to become significant. What significant means is a matter of context, but generally speaking a velocity of at least 50%… …   Wikipedia

  • Jet bundle — In differential geometry, the jet bundle is a certain construction which makes a new smooth fiber bundle out of a given smooth fiber bundle. It makes it possible to write differential equations on sections of a fiber bundle in an invariant… …   Wikipedia

  • Jet (particle physics) — A jet is a narrow cone of hadrons and other particles produced by the hadronization of a quark or gluon in a particle physics or heavy ion experiment. Because of QCD confinement, particles carrying a color charge, such as quarks, cannot exist in… …   Wikipedia

  • Jet quenching — In ultra relativistic heavy ion collisions at center of mass energy of 5.5 TeV at the Large Hadron Collider (LHC), interactions between the high momentum Parton and the hot, dense medium produced in the collisions, are expected to lead to jet… …   Wikipedia

  • Polar jet — You may be looking for relativistic jet, a polar jet emitted at relativistic speed. A polar jet is a phenomenon often seen in astronomy, where streams of matter are emitted along the axis of rotation of a compact object. It is usually caused by… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”