We present the first results of coordinated multi-wavelength observations of
the Galactic black hole GX 339-4 in a canonical low-hard state, obtained during
its 2004 outburst. XMM-Newton observed the source for 2 revolutions, or
approximately 280 ksec; RXTE monitored the source throughout this long stare.
The resulting data offer the best view yet obtained of the inner accretion flow
geometry in the low-hard state, which is thought to be analogous to the
geometry in low-luminosity active galactic nuclei. The XMM-Newton spectra
clearly reveal the presence of a cool accretion disk component, and a
relativistic Fe K emission line. The results of fits made to both components
strongly suggest that a standard thin disk remains at or near to the innermost
stable circular orbit, at least in bright phases of the low-hard state. These
findings indicate that potential links between the inner disk radius and the
onset of a steady compact jet, and the paradigm of a radially-recessed disk in
the low-hard state, do not hold universally. The results of our observations
can best be explained if a standard thin accretion disk fuels a corona which is
closely related to, or consistent with, the base of a compact jet. In a brief
examination of archival data, we show that Cygnus X-1 supports this picture of
the low/hard state. We discuss our results within the context of disk-jet
connections and prevailing models for accretion onto black holes.Comment: 13 pages, 10 figures (6 in color), ApJ, in pres