Accreting millisecond pulsars: one on each hand

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).

Advertised on:
8
2007
Number of authors
3
IAC number of authors
0
Citations
20
Refereed citations
19
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.