Rapid X-ray variability of the gamma-ray binary LS I +61°303

The gamma-ray binary LS I+61 303 has been widely monitored at different wavelengths since its discovery more than sixty years ago. However, the nature of compact object and peculiar behavior system are still largely debated. Aimed investigating rapid X-ray variability 303, we have analysed all archival RXTE/PCA data source, taken between 1996 2011. timing analysis yields a periodicity $P\sim 26.6\pm 0.3$ days, which is statistically compatible with several periodicities reported in literature for 303. Using this period, performed phase-resolved to produce set phase-bin-averaged energy spectra power density spectra. These dominated by weak red noise below 0.1 Hz, show no signal above frequency. amplitude varies mildly phase, shows maximum that coincides dip flux softer photon index. Aside from low-frequency noise, does not provide any significant periodic or quasi-periodic feature