Detection of a hard tail in the X-ray spectrum of the Z source GX 349+2

We present the results of a BeppoSAX observation of the Z source GX 349+2 c overing the energy range 0.1-200 keV. The presence of flares in the light c urve indicates that the source was in the flaring branch during the BeppoSA X observation. We accumulated energy spectra separately for the nonflaring intervals and for the flares. In both cases, the continuum is well describe d by a soft blackbody (kT(BB) similar to 0.5 keV) and a Comptonized spectru m corresponding to electron temperature kT(e) similar to 2.7 keV, optical d epth tau similar to 10 (for a spherical geometry), and seed-photon temperat ure kT(w) similar to 1 keV. All temperatures tend to increase during the fl ares. In the nonflaring emission, a hard tail dominates the spectrum above 30 keV. This can be fit by a power law with photon index similar to2, contr ibuting similar to2% of the total source luminosity over the BeppoSAX energ y range. A comparison with hard tails that are detected in some soft states of black hole binaries suggests that a similar mechanism could originate t hese components in black hole and neutron star systems.