Editing Cygnus X-1 (section)

====Jets====
As accreted matter falls toward the compact object, it loses [[gravitational energy|gravitational potential energy]]. Part of this released energy is dissipated by [[Astrophysical jet|jets]] of particles, aligned [[perpendicular]] to the accretion disk, that flow outward with [[Special relativity|relativistic]] velocities (that is, the particles are moving at a significant fraction of the [[speed of light]]). This pair of jets provide a means for an accretion disk to shed excess energy and [[angular momentum]]. They may be created by [[magnetic field]]s within the gas that surrounds the compact object.<ref name=science300_5627/>

The Cygnus&nbsp;X-1 jets are inefficient radiators and so release only a small proportion of their energy in the [[electromagnetic spectrum]]. That is, they appear "dark". The estimated angle of the jets to the line of sight is 30°, and they may be [[Precession|precessing]].<ref name=apj626_2_1015/> One of the jets is colliding with a relatively dense part of the [[interstellar medium]] (ISM), forming an energized ring that can be detected by its radio emission. This collision appears to be forming a [[nebula]] that has been observed in the [[Visible spectrum|optical wavelengths]]. To produce this nebula, the jet must have an estimated average power of 4–{{val|14|e=36|u=[[erg]]/s}}, or {{val|9|5|e=29|ul=W}}.<ref name=mnras376_3_1341/> This is more than 1,000 times the power emitted by the Sun.<ref name=apj418_457/> There is no corresponding ring in the opposite direction because that jet is facing a lower-density region of the [[Interstellar medium|ISM]].<ref name=nature436_7052_819/>

In 2006, Cygnus&nbsp;X-1 became the first stellar-mass black hole found to display evidence of [[gamma-ray]] emission in the very high-energy band, above {{val|100|ul=GeV}}. The signal was observed at the same time as a flare of hard X-rays, suggesting a link between the events. The X-ray flare may have been produced at the base of the jet, while the gamma rays could have been generated where the jet interacts with the stellar wind of HDE&nbsp;226868.<ref name=apjl665_1_L51/>