Suzaku Observation of X-ray Variability in Soft State LMC X-1

Abstract

This paper reports the results of Suzaku observation of the spectral variation of the black hole binary LMCX-1 in the soft state. The observationwas carried out in 2009 from July 21 to 24. the obtained net count rate was $\sim$30 counts s${}^{-1}$ in the 0.5--50 keV band with $\sim$10% peak-to-peak flux variation. The time-averaged X-ray spectrum cannot be described by a multi-color disk and single Compton component with its reflection, but requires additional Comptonized emissions. This double Compton component model allows a slightly larger inner radius of the multi-color disk, implying a lower spin parameter. Significant spectral evolution was observed above 8 keV along with a flux decrease on a timescale of $\sim$10${}^4$--10${}^5$ s. By spectral fitting, we show that this behavior is well explained by changes in the hard Comptonized emission component in contrast to the maintained disk and soft Comptonized emission.

arXiv comment14 pages, 8 figures, 2 tables, PASJ accepted

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Cited by in corpus (3)

• Testing wind as an explanation for the spin problem in the continuum-fitting method
• MAXI observations of long-term variations of Cygnus X-1 in the low/hard and the high/soft states
• Multi-mission view of extragalactic black hole X-ray binaries LMC X-1 and LMC X-3: evolution of broadband spectral features