OBSERVATIONS of the Seyfert galaxy NGC4151 by Ariel V, OSOI VII and UCSD (refs 1–3 respectively) have demonstrated that it has a relatively flat X-ray spectrum up to photon energies greater than 100 keV. The X-ray luminosity of this object is of the order of 4 × 1043 erg s−1 if a distance of 20 Mpc is assumed, and exceeds the integrated luminosity at all the other observed greater wavelengths. Long-term observations4 by Ariel V indicate that the X-ray emission may originate from a compact object with dimensions less than 8 × 1015 cm, presumably the nucleus of the Galaxy. Here we present the preliminary results of a positive measurement in the low energy γ-ray region of the spectrum, which are in good agreement with the X-ray data and confirm the intense high energy luminosity of the object.
D. Ramsden合作论文数4AJ Dean合作论文数4c paizis合作论文数4Giovanni F. Bignami合作论文数4D. Maccagni合作论文数3Ha Mayerhasselwander合作论文数3b n swanenburg合作论文数3federico perotti合作论文数2g piccinotti合作论文数2r d wills合作论文数EUROPEAN SPACE AGCY,EUROPEAN SPACE RES & TECHNOL CTR,DEPT SPACE SCI,NOORDWIJK,NETHERLANDS2K. Bennett合作论文数2
Gottfried Kanbach合作论文数Max-Planck-Institut fuer extraterrestrische Physik2Wim Hermsen合作论文数2J. Paul合作论文数2R. Buccheri合作论文数2
G. G. Lichti合作论文数2stephen james martin合作论文数1P. G. Shukla合作论文数1b g taylor合作论文数1livio scarsi合作论文数1G DICOCCO合作论文数1L Scarsi合作论文数1Brian Taylor合作论文数1Martin, S. J.合作论文数1G. Villa合作论文数1J. Burger合作论文数1G. Boella合作论文数1Francesco Perotti合作论文数1Piero Mussio合作论文数1R Christopher Butler合作论文数1A. Della Ventura合作论文数ITC - Unità Staccata di Milano - Tecnologie Informatiche Multimediali - Consiglio Nazionale delle Ricerche1R. E. Baker合作论文数1Elmar Pfeffermann合作论文数1J. A. Paul合作论文数1m gorisse合作论文数1
