Millihertz Oscillation Frequency Drift Predicts the Occurrence of Type I X-ray Bursts

Abstract

Millihertz quasi-periodic oscillations reported in three neutron-star low mass X-ray binaries have been suggested to be a mode of marginally stable nuclear burning on the neutron star surface. In this Letter, we show that close to the transition between the island and the banana state, 4U~1636--53 shows mHz QPOs whose frequency systematically decreases with time until the oscillations disappear and a Type I X-ray burst occurs. There is a strong correlation between the QPO frequency $\nu$ and the occurrence of X-ray bursts: when $\nu \gtrsim 9$ mHz no bursts occur, while $\nu \lesssim 9$ mHz does allow the occurrence of bursts. The mHz QPO frequency constitutes the first identified observable that can be used to predict the occurrence of X-ray bursts. If a systematic frequency drift occurs, then a burst happens within a few kilo-seconds after $\nu$ drops below 9 mHz. This observational result confirms that the mHz QPO phenomenon is intimately related with the processes that lead to a thermonuclear burst.

Accepted for publication in ApJ Letters - Uses emulateapj (misspelled author name corrected)

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• Characterizing the Evolving X-Ray Spectral Features During a Superburst from 4U 1636-536
• Millihertz quasi-periodic oscillations in 4U 1636-53 associated with bursts with positive convexity only
• Discovery of a correlation between the frequency of the mHz quasi-periodic oscillations and the neutron-star temperature in the low-mass X-ray binary 4U 1636-53
• Discovery of a soft X-ray 8 mHz QPO from the accreting millisecond pulsar IGR J00291+5934
• Thermonuclear X-ray bursts from LMXB 4U 1636$-$536 observed with AstroSat
• The efficiency of nuclear burning during thermonuclear (Type I) bursts as a function of accretion rate
• The Thermal Stability of Helium Burning on Accreting Neutron Stars
• The stochastic X-ray variability of the accreting millisecond pulsar MAXI J0911-655
• Phase-resolved analyses of mHz quasi-periodic oscillations in 4U 1636-53 using Hilbert-Huang transform
• Detection of millihertz quasi-periodic oscillations in the low-mass X-ray binary 4U 1730--22 with NICER
• The thermonuclear X-ray bursts of 4U 1730-22
• 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
• Drifts of the marginally stable burning frequency in the X-ray binaries 4U 1608--52 and Aql X--1
• A $\sim$100 mHz QPO in the X-ray emission from IGR J17361-4441
• The harmonic component of the millihertz quasi-periodic oscillations in 4U 1636-53
• Quasi-periodic pulse amplitude modulation in the accreting millisecond pulsar IGR J00291+5934
• Thermonuclear Type-I X-ray Bursts and Burst Oscillations from the Eclipsing AMXP Swift J1749.4-2807
• Recurrent Instability in LMXB Accretion Disks: How Strange is GRS 1915+105?
• NuSTAR and AstroSat observations of thermonuclear X-ray bursts with short-recurrence times in 4U 1636$-$536