Astrophysical jet

An astrophysical jet (hereafter 'jet') is an astronomical phenomenon where outflows of ionised matter are emitted as an extended beam along the axis of rotation. Formation and powering astrophysical jets is not fully understood, but it is likely that their origins are from dynamic interactions within accretion disks or from active processes associated with compact central objects: such as black holes, neutron stars or pulsars. When this greatly accelerated matter approaches the speed of light astrophysical jets become relativistic jets as they show effects under special relativity. It is not exactly known how jets are formed in accretion disks or how the matter is accelerated, but it is possibly due to generated tangled magnetic fields that aim two diametrically opposing beams away from the central source by angles only several degrees wide. (c.>1%.)

Many astronomical objects that contain jets include cataclysmic variable stars, X-ray binaries and Gamma ray bursters (GRB). Others are associated with star forming regions including T Tauri stars and Herbig–Haro objects, which are caused by the interaction of jets with the interstellar medium. Bipolar outflows or jets may also be associated with protostars, or with evolved post-AGB stars, planetary nebulae and bipolar nebulae.

Most of the largest and most active jets are created by super massive black holes (SMBH) black holes in the centre of active galaxies such as quasars and radio galaxies or within galaxy clusters. Such jets can exceed millions of parsecs in length.

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