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

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.

arXiv comment4 pages, 3 figures. To appear in the proceedings of the "The Restless High-Energy Universe" (Amsterdam, The Netherlands), 2003, eds. E.P.J. van den Heuvel, J.J.M. in 't Zand, and R.A.M.J. Wijers

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Cited by in corpus (5)

• Non-linear resonance in the accretion disk of a millisecond pulsar
• Physics of accretion in the millisecond pulsar XTE J1751-305
• On the kHz QPO frequency correlations in bright neutron star X-ray binaries
• Discovery of twin kHz quasi periodic oscillations in the low mass X-ray binary XTE J1701-407
• Spectral Analysis of the 2019 and 2022 Outbursts of SAX J1808.4-3658