Temporal and spectral parameters of slow X-ray periodic sources observed during Prognoz 9 mission

• Published in: Advances in space research 1998-01, Vol.22 (7), p.939-942
• Main Authors: Kudryavtsev, M.I., Svertilov, S.I., Bogomolov, V.V.
• Format: Article
• Language: English
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/S0273-1177(98)00141-0

Periodic components in hard X-rays from some objects near the Galactic Center were discovered in the experiment during Prognoz-9 mission. The corresponding period values lay in the range from several hours to several days. Some of these periodic processes were identified with the X-ray binaries which were not known before as eclipse systems: H1705-25 (Nov Oph 1977) - 152 h, Sco X-1 - 62 h, Cen X-4 -8.2 h, 4U1755-33 - 4.4 h. Other periods are still unidentified: 98 h, 69 h, 13 h, 9.4 h, 7.8 h, 3.4 h, 1.96 h. The common property of all these processes is the very complicated form of mean light curves similar to those pulse profiles which were obtained for ordinary “more fast” (with periods less than 1000 s) X-ray pulsars. The energy spectra of these sources are characterized by the values of the effective temperature kT in the range from ∼5 (1.96 h) to >40 keV (152 h).