What is Relativistic jet?
[[File:M87 jet.jpg|thumb|250px|[[Elliptical galaxy]] [[M87]] emitting a relativistic jet, as seen by the [[Hubble Space Telescope]]]] '''Relativistic jets''' are very powerful jets of [[plasma (physics)|plasma]] with speeds close to the speed of light.<ref>{{cite journal|title=What is the structure of relativistic jets in AGN on scales of light days?|journal=Astro2010: The Astronomy and Astrophysics Decadal Survey|volume=2010|pages=310|author=Wehrle A.E; Zacharias N. & Johnston K. 2009 |year=2009|url=http://www.nrao.edu/A2010/whitepapers/rac/Wehrle_AGN_jets_GCT.pdf|display-authors=etal|bibcode=2009astro2010S.310W}}</ref> They are [[emission|emitted]] by the central [[black hole]]s of some [[Active galactic nucleus|active galaxies]] (notably [[radio galaxy|radio galaxies]] and [[quasar]]s), and by the black holes of massive stars and [[neutron star]]s. Their lengths can reach several thousand or even hundreds of thousands of [[light years]].<ref>{{Cite web|last=Biretta J. 1999 |url=http://www.stsci.edu/ftp/science/m87/m87.html|title= Hubble detects faster-than-light motion in Galaxy M87}}</ref><ref>{{cite web|work=Yale University – Office of Public Affairs 2006 | archive-url=https://web.archive.org/web/20080513034113/http://www.yale.edu/opa/newsr/06-06-20-01.all.html|archive-date=2008|title= Evidence for ultra-energetic particles in jet from black hole | date=20 June 2006|url=http://news.yale.edu/2006/06/20/evidence-ultra-energetic-particles-jet-black-hole}}</ref> If the jet speed is close to the [[speed of light]], the effects of the [[special theory of relativity]] are significant. The mechanics behind how jets are created,<ref>{{cite journal|arxiv=astro-ph/0312048|doi=10.1016/S1387-6473(03)00120-9|title=The theory and simulation of relativistic jet formation: towards a unified model for micro- and macroquasars|journal=New Astronomy Reviews|volume=47|issue=6–7|pages=667–672 |last=Meier, David L 2003 |year=2003|bibcode=2003NewAR..47..667M|s2cid=16108597}}</ref><ref>{{cite journal|doi=10.1126/science.1100638 |p