Cygnus X-1
Jets

As accreted matter falls toward the compact object, it loses gravitational potential energy. Part of this released energy is dissipated by jets of particles, aligned perpendicular to the accretion disk, that flow outward with 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 fields within the gas that surrounds the compact object.

The Cygnus 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 precessing. 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 optical wavelengths. To produce this nebula, the jet must have an estimated average power of 4– 14 × 10 erg /s, or (9 ± 5) × 10 W. This is more than 1,000 times the power emitted by the Sun. There is no corresponding ring in the opposite direction because that jet is facing a lower-density region of the ISM.

In 2006, Cygnus X-1 became the first stellar-mass black hole found to display evidence of gamma-ray emission in the very high-energy band, above 100 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 226868.
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