Long-term INTEGRAL and RXTE observations of the X-ray pulsar LMC X-4 |
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Authors: | S S Tsygankov A A Lutovinov |
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Institution: | (1) Space Research Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow, 117810, Russia |
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Abstract: | We analyze the observations of the X-ray pulsar LMCX-4 performed by the INTEGRAL observatory and the All-Sky Monitor (ASM) of the RXTE observatory over a wide energy range. The observed hard X-ray flux from the source is shown to change by more than a factor of 50 (from ~70 mCrab in the high state to ~1.3 mCrab in the low state) on the time scale of the accretion-disk precession period, whose mean value for 1996–2004 was determined with a high accuracy, Pprec = 30.275 ± 0.004 days. In the low state, a flare about 10 h in duration was detected from the source; the flux from the source increased by more than a factor of 4 during this flare. The shape of the pulsar’s broadband spectrum is essentially invariable with its intensity; no statistically significant features associated with the possible resonance cyclotron absorption line were found in the spectrum of the source. |
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Keywords: | pulsars neutron stars X-ray sources |
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