The aperiodic timing behaviour of the accretion-driven millisecond pulsar SAX J1808.4-3658

S. van Straaten; M. van der Klis; R. Wijnands

doi:10.1016/j.nuclphysbps.2004.04.118

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arXiv · astro-ph/0309345

The aperiodic timing behaviour of the accretion-driven millisecond pulsar SAX J1808.4-3658

S. van Straaten·M. van der Klis·R. Wijnands

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Abstract

We studied the aperiodic X-ray timing behaviour of the accreting millisecond pulsar SAX J1808.4-3658. The source was recently found to be the first accreting millisecond pulsar that shows the kilohertz quasi-periodic oscillations (kilohertz QPOs) that are found in many other X-ray binaries with accreting neutron stars. The high frequency of these signals reflects the short dynamical time scales in the region near the compact object where they originate. We find that in addition to the kilohertz QPOs SAX J1808.4-3658 shows several low frequency timing features, based on which the source can be classified as a so-called atoll source. The frequencies of the variability components of the atoll sources follow a universal scheme of correlations. The correlations in SAX J1808.4-3658 are similar but show a shift in upper kilohertz QPO frequency. This discrepancy is perhaps related to a stronger or differently configured magnetic field.

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S. van Straaten, M. van der Klis, R. Wijnands. 2003-09-12. The aperiodic timing behaviour of the accretion-driven millisecond pulsar SAX J1808.4-3658. https://doi.org/10.1016/j.nuclphysbps.2004.04.118

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