The stochastic X-ray variability of the accreting millisecond pulsar IGR J17062-6143

Abstract

This work presents an investigation of the stochastic X-ray variability from the 164 Hz accreting millisecond pulsar IGR J17062-6143, based on regular observations collected with the Neutron Star Interior Composition Explorer between 2017 July and 2020 August. Over this period, the power density spectrum showed a stable morphology, with broad $\sim 25\%$ rms band-limited noise below 16 Hz. Quasi-periodic oscillations (QPOs) were occasionally observed, with the most notably detections including a low-frequency QPO centered at 2.7 Hz and a sharp QPO centered at 115 Hz that may be a 2:3 resonance with the spin frequency. Further, the energy dependence of the band-limited noise is studied through a spectroscopic analysis of the complex covariance in two frequency intervals. It is found that the power law continuum is the primary driver for the observed variability, although the thermal (blackbody) emission also appears to be intrinsically variable in area ($5\%$ rms) and temperature ($1\%$ rms). Notably, the 1 keV emission feature seen in all X-ray spectra of IGR J17062-6143 varies with the same amplitude as the power law, but systematically lags behind that continuum emission. These results appear consistent with a scenario in which a time variable Compton-scattering corona is the primary source for the observed stochastic variability, with the variability observed in the emission feature and at the lowest photon energies being due to the disk reflection of the power law continuum.

13 pages, 5 figures, 3 tables. Accepted for publication in ApJ

References in corpus (19)

• X-ray reverberation around accreting black holes
• INTEGRAL observations of the cosmic X-ray background in the 5-100 keV range via occultation by the Earth
• A quasi-periodic modulation of the iron line centroid energy in the black hole binary H 1743-322
• Geometrical constraints on the origin of timing signals from black holes
• Inclination dependence of QPO phase lags in black hole X-ray binaries
• X-ray time variability across the atoll source states of 4U 1636--53
• The Comptonising medium of the neutron star in 4U 1636-53 through its lower kilohertz Quasi-Periodic Oscillations
• Inclination-dependent spectral and timing properties in transient black hole X-ray binaries
• An in-depth study of a neutron star accreting at low Eddington rate: On the possibility of a truncated disk and an outflow
• Energy Dependent Time Delays of kHz Oscillations due to Thermal Comptonization
• Multi-timescale X-ray reverberation mapping of accreting black holes
• X-ray Reflection and An Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143
• Pulse amplitude depends on kHz QPO frequency in the accreting millisecond pulsar SAX J1808.4-3658
• 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
• Long-term coherent timing of the accreting millisecond pulsar IGR J17062-6143
• On the frequency correlations of low-frequency QPOs with kilohertz QPOs in accreting millisecond X-ray pulsars
• Quasi-periodic pulse amplitude modulation in the accreting millisecond pulsar IGR J00291+5934
• On the impact of an intermediate duration X-ray burst on the accretion environment in IGR J17062-6143