XMM-Newton and NICER measurement of the rms spectrum of the millihertz quasi-periodic oscillations in the neutron-star low-mass X-ray binary 4U 1636-53

Abstract

We used two XMM-Newton and six Neutron Star Interior Composition Explorer (NICER) observations to investigate the fractional rms amplitude of the millihertz quasi-periodic oscillations (mHz QPOs) in the neutron-star low-mass X-ray binary 4U 1636-53. We studied, for the first time, the fractional rms amplitude of the mHz QPOs vs. energy in 4U 1636-53 down to 0.2 keV. We find that, as the energy increases from 0.2 keV to 3 keV, the rms amplitude of the mHz QPOs increases, different from the decreasing trend that has been previously observed above 3 keV. This finding has not yet been predicted by any current theoretical model, however, it provides an important observational feature to speculate whether a newly discovered mHz oscillation originates from the marginally stable nuclear burning process on the neutron star surface.

arXiv commentPublished in ApJ, 10 pages, 5 figures

References in corpus (24)

• Dependence of the Frequency of the Kilohertz Quasi-Periodic Oscillations on X-ray Count Rate and Colors in 4U 1608-52
• A systematic analysis of the broad Fe Kalpha line in neutron star LMXBs with XMM-Newton
• Millihertz Quasi-Periodic Oscillations from Marginally Stable Nuclear Burning on an Accreting Neutron Star
• New class of low frequency QPOs: signature of nuclear burning or accretion disk instabilities?
• Millihertz quasi-periodic oscillations and thermonuclear bursts from Terzan 5: A showcase of burning regimes
• A strong and broad iron line in the XMM-Newton spectrum of the new X-ray transient and black-hole candidate XTE J1652-453
• Millihertz Oscillation Frequency Drift Predicts the Occurrence of Type I X-ray Bursts
• Thermonuclear X-ray Bursts: Theory vs. Observations
• The effect of rotation on the stability of nuclear burning in accreting neutron stars
• NICER Observes the Effects of an X-Ray Burst on the Accretion Environment in Aql X-1
• Ignition latitude and the shape of Type I X-ray bursts
• Reaction Rate and Composition Dependence of the Stability of Thermonuclear Burning on Accreting Neutron Stars
• The cooling phase of Type-I X-ray bursts in 4U 1636-53
• Broad iron line in the fast spinning neutron-star system 4U 1636-53
• The 2015 outburst of the accretion-powered pulsar IGR J00291+5934: INTEGRAL and Swift observations
• Spectral and timing analysis of the mHz QPOs in the neutron-star low-mass X-ray binary 4U 1636-53
• NICER Discovers mHz Oscillations in the "Clocked" Burster GS 1826-238
• X-ray Burst Oscillations: From Flame Spreading to the Cooling Wake
• Discovery of millihertz quasi-periodic oscillations in the X-ray binary EXO 0748--676
• NICER Detects a Soft X-ray Kilohertz Quasi-periodic Oscillation in 4U 0614+09
• Millihertz quasi-periodic oscillations in 4U 1636-53 associated with bursts with positive convexity only
• Discovery of a soft X-ray 8 mHz QPO from the accreting millisecond pulsar IGR J00291+5934
• Discovery of an accretion-rate independent absolute RMS amplitude of millihertz quasi-periodic oscillations in 4U 1636-53
• Ionisation state of the accretion disc in the neutron-star low-mass X-ray binary 4U 1728-34

Cited by in corpus (5)

• The evolution of the high-frequency variability in the black hole candidate GRS 1915+105 as seen by RXTE
• Detection of millihertz quasi-periodic oscillations in the low-mass X-ray binary 4U 1730--22 with NICER
• Drifts of the marginally stable burning frequency in the X-ray binaries 4U 1608--52 and Aql X--1
• The harmonic component of the millihertz quasi-periodic oscillations in 4U 1636-53
• The mHz quasi-regular modulations of 4U 1630--47 during its 1998 outburst