SIGMA-DETECTION OF HARD X-RAY-EMISSION FROM THE TERZAN-1 GLOBULAR-CLUSTER

During the survey of the Galactic center region performed by the hard X-ray telescope SIGMA aboard the Granat space observatory, a persisten t source coincident with the Terzan 1 globular cluster has been observ ed. This source may be associated with the persistent X-ray source X17 32-304 studied by EXOSAT, ROSAT, and ART-P and with the X-ray burster source detected by Hakucho in Terzan 1. The source appears at the 5.5 sigma level in the SIGMA images in the 40-75 keV energy range. There i s no evidence for time variability, and the photon spectrum is reprodu ced by a thermal bremsstrahlung law with a temperature equal to 33(-12 )(+32) keV as well as by a power law with spectral index equal to -3.2 +/- 0.7. The luminosity in the 40-75 keV energy range is equal to 4.0 +/- 0.8 x 10(35) ergs s(-1), assuming a distance of 10 kpc. This hard X-ray emission may come from a low-mars X-ray binary with a neutron s tar as the compact member.