7 research outputs found
Long-Term INTEGRAL and RXTE Observations of the X-Ray Pulsar LMC X-4
We analyze the observations of the X-ray pulsar LMC X-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.Comment: 16 pages, 5 figures, Astronomy Letters, 31, 380-387 (2005