HARD X-RAY SIGNATURE OF PLASMA EJECTION IN THE GALACTIC JET SOURCE GRS-1915+105

Since its discovery in 1992, GRS 1915+105 has undergone numerous X-ray outbursts with luminosities ranging from 10(37) to a few x10(38) ergs s(-1) (20-100 keV). The radio counterpart sometimes exhibits opticall y thin flares (0.1-1 Jy) in the GHz frequency range associated with su perluminal ejection of radio-emitting plasma. Here we examine the temp oral and spectral evolution of the hard X-ray and radio emission of GR S 1915+105. We find, during a 1993 December to 1994 April spring outbu rst, an exceptionally high level of activity in the GHz band coupled w ith the appearance of several ejection events when compared to other m onitoring results. Within the derived uncertainty of the ejection time s and the subsequent appearance of radio flares, there appear to be de creases or dips in the hard X-ray flux anticorrelated with increases i n radio emission. These observations suggest an interaction between th e hard X-ray emission region and jet production, and they imply the re direction of accretion material into jets on timescales of days or les s. Although jet production may occur at high accretion rates, other fa ctors must be important, i.e., at times, something must ''break'' the correlative nature of the radio and X-ray bands. We also search for lo ng-term periodicities in the X-ray data for evidence of a binary signa ture in light of recent suggestions that GRS 1915+105 may be a high-ma ss system.