Quasi-periodic pulse amplitude modulation in the accreting millisecond pulsar IGR J00291+5934

Abstract

We introduce a new method for analysing the aperiodic variability of coherent pulsations in accreting millisecond X-ray pulsars. Our method involves applying a complex frequency correction to the time-domain light curve, allowing for the aperiodic modulation of the pulse amplitude to be robustly extracted in the frequency domain. We discuss the statistical properties of the resulting modulation spectrum and show how it can be correlated with the non-pulsed emission to determine if the periodic and aperiodic variability are coupled processes. Using this method, we study the 598.88 Hz coherent pulsations of the accreting millisecond X-ray pulsar IGR J00291+5934 as observed with the Rossi X-ray Timing Explorer and XMM-Newton. We demonstrate that our method easily confirms the known coupling between the pulsations and a strong 8 mHz QPO in XMM-Newton observations. Applying our method to the RXTE observations, we further show, for the first time, that the much weaker 20 mHz QPO and its harmonic are also coupled the pulsations. We discuss the implications of this coupling and indicate how it may be used to extract new information on the underlying accretion process.

arXiv comment12 pages, 7 figures, 1 table. Accepted for publication in ApJ

References in corpus (34)

• A Unified Description of the Timing Features of Accreting X-ray Binaries
• The flux-dependent amplitude of broadband noise variability in X-ray binaries and active galaxies
• On the Nature of the X-ray Emission from the Accreting Millisecond Pulsar SAX J1808.4-3658
• X-Ray Variability Coherence: How to Compute it, What it Means, and How it Constrains Models of Cyg X-1 and GX 339-4
• The long-term evolution of the spin, pulse shape, and orbit of the accretion-powered millisecond pulsar SAX J1808.4-3658
• A quasi-periodic modulation of the iron line centroid energy in the black hole binary H 1743-322
• Discovery of the accretion-powered millisecond X-ray pulsar IGR J00291+5934
• INTEGRAL and RXTE observations of accreting millisecond pulsar IGR J00291+5934 in outburst
• Physics of accretion in the millisecond pulsar XTE J1751-305
• The Accreting Millisecond X-ray Pulsar IGR J00291+5934: Evidence for a Long Timescale Spin Evolution
• Relativistic precession around rotating neutron stars: Effects due to frame-dragging and stellar oblateness
• Phase-resolved X-ray spectroscopy of the millisecond pulsar SAX J1808.4-3658
• New class of low frequency QPOs: signature of nuclear burning or accretion disk instabilities?
• Millihertz Quasi-Periodic Oscillations from Marginally Stable Nuclear Burning on an Accreting Neutron Star
• Relations Between Timing Features and Colors in Accreting Millisecond Pulsars
• The magnetic field strengths of accreting millisecond pulsars
• Phase-resolved spectroscopy of low frequency quasi-periodic oscillations in GRS 1915+105
• A Double Outburst from IGR J00291+5934: Implications for Accretion Disk Instability Theory
• An alternative interpretation of the timing noise in accreting millisecond pulsars
• Millihertz Oscillation Frequency Drift Predicts the Occurrence of Type I X-ray Bursts
• SAX J1808.4-3658 and the origin of X-ray variability in X-ray binaries and active galactic nuclei
• Reaction Rate and Composition Dependence of the Stability of Thermonuclear Burning on Accreting Neutron Stars
• Observations of the 599 Hz Accreting X-ray Pulsar IGR J00291+5934 during the 2004 Outburst and in Quiescence
• Spectral and timing properties of IGR J00291+5934 during its 2015 outburst
• On the relationship between the periodic and aperiodic variability of accreting X-ray pulsars
• The 2015 outburst of the accretion-powered pulsar IGR J00291+5934: INTEGRAL and Swift observations
• High frequency features in the 1998 outburst of 4U 1630-47
• Discovery of the INTEGRAL X/Gamma-ray transient IGR J00291+5934: a Comptonised accreting ms pulsar ?
• An accreting millisecond pulsar with black hole-like X-ray variability: IGR J00291+5934
• Testing the relativistic precession model using low frequency and kHz quasi-periodic oscillations in neutron star low mass X-ray binaries with known spin
• Discovery of a soft X-ray 8 mHz QPO from the accreting millisecond pulsar IGR J00291+5934
• The stochastic X-ray variability of the accreting millisecond pulsar MAXI J0911-655
• Coupling Between Periodic and Aperiodic Variability in SAX J1808.4-3658
• Discovery of 1-5 Hz flaring at high luminosity in SAX J1808.4-3658

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• Long-term coherent timing of the accreting millisecond pulsar IGR J17062-6143
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