X-ray and near-infrared (J -H-Ks) observations of the galactic black-hole binary GX 339-4 in the low/hard state were performed with Suzaku and IRSF in 2009 March. The spectrum in the 0.5-300 keV band is dominated by thermal Comptonization of multicolor disk photons, with a small contribution from a direct disk component, indicating that the inner disk is almost fully covered by hot corona with an electron temperature of ≅175 keV. The Comptonizing corona has at least two optical depths, τ ≅ 1, 0.4. Analysis of the iron-K line profile yields an inner-disk radius of (13.3+6.4 -6.0)Rg (Rg represents the gravitational radius GM=c2), with the best-fit inclination angle of ≅50°. This radius is consistent with that estimated from the continuum fit by assuming the conservation of photon numbers in Comptonization. Our results suggest that the standard disk of GX 339-4 is likely truncated before reaching the innermost stable circular orbit (for a non-rotating black hole) in the low/hard states at ∼1% of the Eddington luminosity. The one-day averaged near-infrared light curves are found to be correlated with hard X-ray flux with FKs ∝ F 0.45 X . The flatter near-infrared νFν spectrum than the radio one suggests that the optically thin synchrotron radiation from the compact jets dominates the near-infrared flux. Based on a simple analysis, we estimate the magnetic field and size of the jet base to be 5 × 104G and 6 × 108 cm, respectively. The synchrotron self Compton component is estimated to be approximately 0.4% of the total X-ray flux.
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