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, P prec = 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.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
C. Chevalier and S. Ilovaisky, Astron. Astrophys. 59, L9 (1977).
W. I. Clarkson, P. A. Charles, M. I. Coe, et al., Mon. Not. R. Astron. Soc. 343, 1213 (2003).
N. A. Eismont, A. V. Ditrikh, G. Janin, et al., Astron. Astrophys. 411, L37 (2003).
A. Epstein, J. Delvaille, H. Helmken, et al., Astrophys. J. 216, 103 (1977).
P. Ghosh and F. Lamb, Astrophys. J. 234, 296 (1979).
C. Jones and W. Forman, Astrophys. J. 209, L131 (1976).
R. L. Kelley, J. G. Jernigan, A. Levine, et al., Astrophys. J. 264, 568 (1983).
A. La Barbera, L. Burderi, T. Di Salvo, et al., Astrophys. J. 553, 375 (2001).
F. L. Lang, A. M. Levine, M. Bautz, et al., Astrophys. J. 246, L21 (1981).
D. A. Leahy, R. F. Elsner, and M. C. Weisskopf, Astrophys. J. 272, 256 (1983).
F. Lebrum, J. P. Leray, P. Lavocat, et al., Astron. Astrophys. 411, L141 (2003).
A. Levine, S. Rappaport, A. Putney, et al., Astrophys. J. 381, 101 (1991).
A. Levine, S. Rappaport, and G. Zojcheski, Astrophys. J. 541, 194 (2000).
F. Li, S. Rappaport, and A. Epstein, Nature 271, 37 (1978).
N. Lund, S. Brandt, C. Budtz-Joergesen, et al., Astron. Astrophys. 411, L231 (2003).
A. A. Lutovinov, S. A. Grebenev, M. N. Pavlinsky, and R. A. Sunyaev, Pis’ma Astron. Zh. 26, 803 (2000) [Astron. Lett. 26, 765 (2000)].
A. A. Lutovinov, S. V. Mol’kov, and M. G. Revnivtsev, Pis’ma Astron. Zh. 29, 803 (2003) [Astron. Lett. 29, 713 (2003)].
A. A. Lutovinov, S. S. Tsygankov, M. G. Revnivtsev, et al., in Proceedings of the V INTEGRAL Workshop, ESA SP 552, 253 (2004).
T. Mihara, PhD Thesis (Univ. Tokyo, Tokyo, 1995).
S. Naik and B. Paul, Astron. Astrophys. 401, 265 (2003).
B. Paul and S. Kitamoto, J. Astrophys. Astron. 23, 33 (2002).
M. G. Revnivtsev, R. A. Syunyaev, D. A. Varshalovich, et al., Astron. Lett. 30, 382 (2004).
P. E. Shtykovskiy, A. A. Lutovinov, M. R. Gilfanov, and R. A. Sunyaev, Pis’ma Astron. Zh. 31, 284 (2005) [Astron. Lett. 31, 258 (2005)].
G. K. Skinner, S. Shulman, and G. Share, Astrophys. J. 240, 619 (1980).
H. Tananbaum, H. Gursky, E. Kellog, et al., Astrophys. J. 174, L143 (1972).
S. S. Tsygankov and A. A. Lutovinov, Pis’ma Astron. Zh. 31, 99 (2005) [Astron. Lett. 31, 88 (2005)].
P. Ubertini, F. Lebrum, G. Di Cocco, et al., Astron. Astrophys. 411, L131 (2003).
N. White, J. Swank, and S. Holt, Astrophys. J. 270, 771 (1983).
C. Winkler, T. J.-L. Courvoisier, G. Di Cocco, et al., Astron. Astrophys. 411, L1 (2003).
J. W. Woo, G. W. Clark, and A. M. Levine, Astrophys. J. 449, 880 (1995).
J. W. Woo, G. W. Clark, A. M. Levine, et al., Astrophys. J. 467, 811 (1996).
Author information
Authors and Affiliations
Additional information
__________
Translated from Pis’ma v Astronomicheski\(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l} \) Zhurnal, Vol. 31, No. 6, 2005, pp. 427–436.
Original Russian Text Copyright © 2005 by Tsygankov, Lutovinov.
Rights and permissions
About this article
Cite this article
Tsygankov, S.S., Lutovinov, A.A. Long-term INTEGRAL and RXTE observations of the X-ray pulsar LMC X-4. Astron. Lett. 31, 380–387 (2005). https://doi.org/10.1134/1.1940110
Received:
Issue Date:
DOI: https://doi.org/10.1134/1.1940110