Spectral variations of the X-ray binary pulsar LMC X-4 during its long period intensity variation and a comparison with Her X-1

摘要: We present spectral variations of the binary X-ray pulsar LMC X-4 using RXTE/PCA observations at different phases its 30.5 day long super-orbital period. Only out eclipse data were used for this study. During high state period X-4, spectrum is well described by a energy cut-off power-law with photon index in range 0.7-1.0 and an iron emission line. In low state, found to be flatter 0.5-0.7. A direct correlation detected between continuum flux 7-25 keV band line flux, The equivalent width highly variable during intensity whereas it remains almost constant It observed that are similar those Her X- I (using data). These results suggest geometry region where produced visibility respect phase X-1. remarkable difference these two systems absorption column density X-1 but not X-4.