Open AccessOpening angles, Lorentz factors and confinement of X‐ray binary jets
Author(s) -
MillerJones J. C. A.,
Fender R. P.,
Nakar E.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10092.x
Subject(s) - physics , lorentz factor , astrophysics , lorentz transformation , astrophysical jet , jet (fluid) , active galactic nucleus , binary number , transverse plane , lorentz force , doppler effect , classical mechanics , astronomy , magnetic field , mechanics , quantum mechanics , galaxy , structural engineering , engineering , arithmetic , mathematics
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.