Abstract
We present the results of our comparative timing and spectral analysis of the high and low (off) states in the X-ray pulsar Her X-1 based on data from the ART-P telescope onboard the Granat observatory. A statistically significant (several mCrab) persistent flux with a simple power-law spectrum was detected during the low state. The spectral slope changed from observation to observation by almost a factor of 2. Pulsations were detected only during the high state of the source, when its flux was a factor of ∼25 larger than the low-state flux. The spectral shape of Her X-1 in its high state was complex, with the parameters depending on pulse phase.
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Translated from Pis’ma v Astronomicheski\(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l} \) Zhurnal, Vol. 26, No. 11, 2000, pp. 803–812.
Original Russian Text Copyright © 2000 by Lutovinov, Grebenev, Pavlinsky, Sunyaev.
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Lutovinov, A.A., Grebenev, S.A., Pavlinsky, M.N. et al. Spectral variability of the X-ray pulsar Hercules X-1. Astron. Lett. 26, 691–698 (2000). https://doi.org/10.1134/1.1323276
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DOI: https://doi.org/10.1134/1.1323276