FORMATION OF A JET IN THE GALACTIC-CENTER BLACK-HOLE CANDIDATE 1E-1740.7-2942

The Galactic center object 1E 1740.7-2942 is apparently a source of e+e- annihilation radiation and has recently been associated with a double-sided radio jet at lambda = 6 and lambda = 20 cm. We here extend our earlier model for the gamma-ray continuum emission to encompass the formation of the jet, and discuss the ensuing jet structure. We find that due to gammagamma interactions in the intense radiation field produced within the inner approximately 20 Schwarzschild radii (r(g)) of the accretion disk, more than 5 x 10(43) pairs s-1 stream outward and are accelerated by Compton scatterings to velocities as high as approximately 0.7c. Roughly 90% of these pairs annihilate at the base of the nascent jet (within approximately 40 r(g) of the black hole) forming the broad (approximately 240 keV) annihilation line observed by SIGMA on GRANAT. The remainder (less than or similar to 6 x 10(42) pairs s-1) escape into the enshrouding cloud and beyond, and presumably contribute to the formation of both the steady and the time-variable components of the narrow annihilation line observed from the bulge. However, before the pairs annihilate, they radiate via synchrotron emission as they spiral in the cloud's ambient magnetic field. We show that the physical conditions required to account for the broad gamma-ray line seen in the high state and the implied conditions in the normal state are consistent with the pair density and velocity required to form the large-scale jet, the jet's shape, and its radio spectrum and luminosity.