2015MNRAS.451.4253R

We report results of our search for fast oscillations in light curve of one of the brightest accretion powered pulsars on the sky V0332+53 with the help of data of the PCA spectrometer of the RXTE (Rossi X-ray Timing Explorer) observatory. In course of this search we have carefully explored complications appearing if one uses only sub-bands of the total bandpass of the PCA spectrometer. We show that light curves collected in the soft sub-band of the PCA spectrometer contains an additional instrumental noise, light curves of harder sub-bands lack some fraction of the anticipated Poisson noise. We show that this noise is caused by a cross-talk of energy bands, which lasts up to ∼ 200µs. One hypothesis is that these effects are caused by temporarily drop of the PCA detector gain after any occurred event due to slowly moving ions in the detector volume. In order to avoid this effect we searched for fast oscillations in flux of V0332+53 only in the total bandpass of the PCA spectrometer 2-60 keV. We have not detected any quasi-periodic oscillations in light curve of the source with an upper limit at the level of 0.5 percent in the Fourier frequency range 200-1500 Hz.