The stochastic X-ray variability of the accreting millisecond pulsar MAXI J0911-655

Abstract

In this work I report on the stochastic X-ray variability of the 340 Hz accreting millisecond pulsar MAXI J0911-655. Analyzing pointed observations of the XMM-Newton and NuSTAR observatories I find that the source shows broad band-limited stochastic variability in the $0.01-10$ Hz range, with a total fractional variability of $\sim 24\%$ rms in the $0.4-3$ keV energy band, which increases to $\sim 40\%$ rms in the $3-10$ keV band. Additionally a pair of harmonically related quasi-periodic oscillations are discovered. The fundamental frequency of this harmonic pair is observed between frequencies of $62$ mHz and $146$ mHz. Like the band-limited noise, the amplitude of the QPOs show a steep increase as a function of energy, suggesting they share a similar origin, which is likely the inner accretion flow. Based on their energy dependence and their frequency relation with respect to the noise terms, the QPOs are identified as Low-Frequency oscillations, and discussed in terms of Lense-Thirring precession model.

9 pages, 4 figures, 1 table. Accepted for publication in ApJ

References in corpus (10)

• A quasi-periodic modulation of the iron line centroid energy in the black hole binary H 1743-322
• No Time for Dead Time: Timing analysis of bright black hole binaries with NuSTAR
• X-ray time variability across the atoll source states of 4U 1636--53
• Tomographic reflection modelling of quasi-periodic oscillations in the black hole binary H 1743-322
• Identification of black hole power spectral components across all canonical states
• Millihertz Oscillation Frequency Drift Predicts the Occurrence of Type I X-ray Bursts
• Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808
• Testing the relativistic precession model using low frequency and kHz quasi-periodic oscillations in neutron star low mass X-ray binaries with known spin
• The aperiodic X-ray variability of the accreting millisecond pulsar SAX J1808.4-3658
• Discovery of a soft X-ray 8 mHz QPO from the accreting millisecond pulsar IGR J00291+5934

Cited by in corpus (6)

• Phase-resolved spectroscopy of a quasi-periodic oscillation in the black hole X-ray binary GRS 1915+105 with NICER and NuSTAR
• X-ray Spectral and Timing evolution of MAXI J1727-203 with NICER
• Detection of a strong ~2.5 Hz modulation in the Newly Discovered Millisecond Pulsar MAXI J1816-195
• X-ray polarimetry-timing
• Quasi-periodic pulse amplitude modulation in the accreting millisecond pulsar IGR J00291+5934
• The NuSTAR view of Ultra-Compact X-ray Binaries