The Power Spectral Properties of the Z Source GX 340+0

We present an analysis of ~390 ksec of data of the Z source GX 340+0 takenduring 24 observations with the Rossi X-ray Timing Explorer satellite. Wereport the discovery of a new broad component in the power spectra. Thefrequency of this component varied between 9 and 14 Hz, and remained close tohalf that of the horizontal branch quasi-periodic oscillations (HBO). Its rmsamplitude was consistent with being constant around ~5%, while its FWHMincreased with frequency from 7 to 18 Hz. If this sub-HBO component is thefundamental frequency, then the HBO and its second harmonic are the second andfourth harmonic component, while the third harmonic was not detected. This issimilar to what was recently found for the black hole candidate XTE J1550-564.The profiles of both the horizontal- and the normal branch quasi-periodicoscillation peaks were asymmetric when they were strongest. We describe this interms of a shoulder component at the high frequency side of the quasi-periodicoscillation peak, whose rms amplitudes were approximately constant at ~4% and\~3%, respectively. The peak separation between the twin kHz quasi-periodicoscillations was consistent with being constant at 339+-8 Hz but a trendsimilar to that seen in, e.g. Sco X-1 could not be excluded. We discuss ourresults within the framework of the various models which have been proposed forthe kHz QPOs and low frequency peaks.