Observations of the X-ray binaries 4U 1700-37 and GRO J1655-40 during the Grif experiment onboard the mir orbiting station |
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| Authors: | M I Kudryavtsev S I Svertilov V V Bogomolov |
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| Institution: | (1) Space Research Institute, Russian Academy of Sciences, ul. Profsoyuznaya 84/32, Moscow, 117810, Russia;(2) Institute of Nuclear Physics, Moscow State University, Vorob’evy gory, Moscow, 119899, Russia |
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| Abstract: | Various areas of the sky, including the Galactic-center region and the region with the X-ray binaries 4U 1700-37 and GRO J1655-40, were observed in the hard (10–300 keV) energy range during the Grif experiment onboard the Mir orbiting station. An epoch-folding analysis of the data has revealed periodicities with periods of 82 and 62 h, which are equal to the orbital periods of 4U 1700-37 and GRO J1655-40. Previously, these periodicities were observed during the Prognoz-9 X-ray experiment. Periodicities with periods in the range of days, 98 and 152 h, which were also observed during the Prognoz-9 experiment, were not revealed by the Grif data. We obtained upper limits on the intensities of these periodicities in various energy ranges. For the 62-h periodicity, we constructed an average 25–50-keV light curve and estimated the spectral flux density, which characterizes the intensity of the periodic component at different energies in different observing intervals during 1995–1997. The Prognoz-9 and Grif observations of GRO J1655-40 are compared with its CGRO, RXTE, and BeppoSax observations. The orbital periodicity is shown to manifest itself in the hard emission from the extremely bright X-ray transient GRO J1655-40, a likely black-hole candidate, even at the epochs between its X-ray outbursts. |
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| Keywords: | space-borne observatories X-ray binaries periodicities transients X-ray novae |
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