AAS 200th meeting, Albuquerque, NM, June 2002
Session 51. The New Radio Universe
Topical Session Oral, Wednesday, June 5, 2002, 8:30-10:00am, 10:45am-12:30pm, 2:30-4:00pm, 4:15-6:00pm, Ballroom C

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[51.03] Microquasars: Relativity for the Impatient

M.P. Rupen (NRAO)

The first superluminal jet source in our Galaxy was discovered by Mirabel & Rodriguez in 1994. Since then relativistic jets have become the new paradigm for explaining radio emission from X-ray binaries, based primarily on new imaging observations from telescopes like the Very Large Array, the Multi-Element Radio Linked Interferometer Network, and the Very Long Baseline Array. Recent results include evidence for a direct coupling between the accretion disk and the jet in GRS 1915+105; imaging of evolving jet lobes in Scorpius~X-1; the detection of ``anomalous emission" away from the jet axis in SS\,433; and a confusing series of VLA and VLBA observations of Cygnus X-3, which show that the jet is often one-sided on small scales, and two-sided further out. The data on both SS\,433 and Cygnus~X-3 have been interpreted in terms of a dense wind from either the accretion disk or the companion star. The extragalactic model of twin jets made asymmetric by relativistic effects is brilliantly successful in some cases, and inadequate in others; and jet inclinations derived under that assumption continue to show major disagreements with better and better optical orbital determinations. Radio polarization measurements should in principle help sort out the orientation and even the strength of the magnetic fields, but these are surprisingly sparse in the literature; indeed, circular polarization has received at least as much attention as linear, with interesting implications for the nature of the relativistic particles. Finally, while the energetic importance of the outflowing material has long been realized, some are now suggesting that the jets are important sources of photons as well, and indeed may be directly connected to the hot accretion disk corona seen in X-rays. I conclude with a brief preview of the exciting results to be expected from the new expansion projects currently under way at MERLIN and the VLA.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.