Opening angles, Lorentz factors and confinement of X-ray binary jets |
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Authors: | J C A Miller-Jones R P Fender E Nakar |
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Institution: | Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, the Netherlands;School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ;Theoretical Astrophysics, Caltech, Pasadena, CA 91125, USA |
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Abstract: | We present a collation of the available data on the opening angles of jets in X-ray binaries, which in most cases are small (?10°). Under the assumption of no confinement, we calculate the Lorentz factors required to produce such small opening angles via the transverse relativistic Doppler effect. The derived Lorentz factors, which are in most cases lower limits, are found to be large, with a mean >10, comparable to those estimated for active galactic nuclei (AGN) and much higher than the commonly assumed values for X-ray binaries of 2–5. Jet power constraints do not, in most cases, rule out such high Lorentz factors. The upper limits on the opening angles show no evidence for smaller Lorentz factors in the steady jets of Cygnus X-1 and GRS 1915+105. In those sources in which deceleration has been observed (notably XTE J1550?564 and Cygnus X-3), some confinement of the jets must be occurring, and we briefly discuss possible confinement mechanisms. It is however possible that all the jets could be confined, in which case the requirement for high bulk Lorentz factors can be relaxed. |
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Keywords: | relativity stars: winds outflows ISM: jets and outflows X-rays: binaries |
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