We study the correlations between timing and X-ray spectral properties in the low mass X-ray binary 4U 0614+09 using a large ( 265-ks ) data set obtained with the Rossi X-ray Timing Explorer .
We find strong quasi-periodic oscillations ( QPOs ) of the X-ray flux , like the kilohertz QPOs in many other X-ray binaries with accreting neutron stars , with frequencies ranging from 1329 Hz down to 418 Hz and , perhaps , as low as 153 Hz .
We report the highest frequency QPO yet from any low mass X-ray binary at 1329 \pm 4 Hz , which has implications for neutron star structure .
This QPO has a 3.5 \sigma single-trial significance , for an estimated 40 trials the significance is 2.4 \sigma .
Besides the kilohertz QPOs , the Fourier power spectra show four additional components : high frequency noise ( HFN ) , described by a broken power–law with a break frequency between 0.7 and 45 Hz , very low frequency noise ( VLFN ) , which is fitted as a power–law below 1 Hz , and two broad Lorentzians with centroid frequencies varying from 6 to 38 Hz and 97 to 158 Hz , respectively .
We find strong correlations between the frequencies of the kilohertz QPOs , the frequency of the 6 - 38 Hz broad Lorentzian , the break frequency of the HFN , the strength of both the HFN and the VLFN and the position of the source in the hard X-ray color vs. intensity diagram .
The frequency of the 97 - 158 Hz Lorentzian does not correlate with these parameters .
We also find that the relation between power density and break frequency of the HFN is similar to that established for black hole candidates in the low state .
We suggest that the changing mass accretion rate is responsible for the correlated changes in all these parameters .