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All X-ray light curves of nova V4743 Sgr (2002), taken during and afteroutburst, contain a 0.75 mHz periodic signal that can most plausibly beinterpreted as being excited by the rotation of the white dwarf in anintermediate polar system. This interpretation faces the challenge of anapparent multi-frequency nature of this signal in the light curves taken days180 and 196 after outburst. We show that the multi-sine fit method, based on asuperposition of two sine functions, yields two inherently indistinguishablesolutions, i.e. the presence of two close frequencies, or a single signal withconstant frequency but variable modulation amplitude. Using a power spectrumtime map, we show that on day 180, a reduction of the modulation amplitude ofthe signal coincides with a substantial overall flux decline while on day 196,the signal was only present during the first half of the observation. Supportedby simulations, we show that such variations in amplitude can lead to falsebeating that manifests itself as a multiple signal if computing a periodogramover the full light curve. Therefore, the previously proposed double frequencynature of both light curves was probably an artefact while we consider a singlesignal with frequency equal to the white dwarf rotation as more plausible.

Counter evidence against multiple frequency nature of 0.75 mHz oscillation in V4743 Sgr