Low and high frequency quasi-periodic oscillations in 4U1915-05. Relation with source state

Using Rossi X-ray Timing Explorer (RXTE) observations, we have discovered both low (5-80 Hz, LF) and high (200–1300 Hz, HF) frequency Quasi Periodic Oscillations (QPOs) from the Low Mass X-ray Binary (LMXB) 4U1915-05. We find that the frequencies of the LF and HF QPOs positively correlate, suggesting that both QPOs are produced by related mechanisms. Their properties also depend upon the spectral state of the X-ray source. In this paper, we study the QPOs as a function of the source count rate and its position in the color-color diagram. We conclude that the timing behavior of the source better correlates with the latter parameter.