Investigation of diffuse hard X-ray emission from the massive star-forming region NGC 6334

Chandra ACIS-I data of the molecular cloud and H II region complex NGC 6334 were analyzed. The hard X- ray clumps detected with ASCA (Sekimoto and coworkers) were resolved into 792 point sources. After removing the point sources, an extended X- ray emission component was detected over a 5; 9 pc2 region, with the 0.5-8 keV absorption-corrected luminosity of 2; 1033 ergs s(-1). The contribution from faint point sources to this extended emission was estimated as at most similar to 20%, suggesting that most of the emission is diffuse in nature. The X- ray spectrum of the diffuse emission was observed to vary from place to place. In tenuous molecular cloud regions with hydrogen column density of ( 0: 5 1); 10(22) cm(-2), the spectrum can be represented by a thermal plasma model with temperatures of several keV. The spectrum in dense cloud cores exhibits harder continuum, together with higher absorption of more than similar to 3; 10(22) cm(-2). In some of such highly obscured regions, the spectra show extremely hard continua equivalent to a photon index of similar to 1, and favor a nonthermal interpretation. These results are discussed in the context of thermal and nonthermal emission, both powered by fast stellar winds from embedded young early-type stars through shock transitions.