Bibcode
                                    
                            Linares, Manuel; van der Klis, Michiel; Wijnands, Rudy
    Bibliographical reference
                                    THE MULTICOLORED LANDSCAPE OF COMPACT OBJECTS AND THEIR EXPLOSIVE ORIGINS. AIP Conference Proceedings, Volume 924, pp. 629-634 (2007).
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                        8
            
                        2007
            
  Citations
                                    29
                            Refereed citations
                                    26
                            Description
                                    We report on the X-ray aperiodic timing analysis of two accreting
millisecond pulsars: XTE J1807-294 and IGR J00291+5934. On the one hand,
we discovered in XTE J1807-294 seven pairs of simultaneous kilohertz
quasi-periodic oscillations (kHz QPOs) separated in frequency by nearly
the spin frequency of the neutron star. This confirms the suspected
dichotomy in the frequency separation of kHz QPOs: sometimes once and
sometimes half the spin frequency. On the other hand, we found an
extreme behavior in the power spectra of IGR J00291+5934: very strong
variability at very low frequencies. Namely, the fractional amplitude of
the variability was ~50%, the highest value found so far in a neutron
star system.