The Latitude of Type I X-Ray Burst Ignition on Rapidly Rotating Neutron Stars

Abstract

We investigate the latitude at which type I X-ray bursts are ignited on rapidly rotating accreting neutron stars. We find that, for a wide range of accretion rates, ignition occurs preferentially at the equator, in accord with the work of Spitkovsky et al. However, for a range of accretion rates below the critical rate above which bursts cease, ignition occurs preferentially at higher latitudes. The range of accretion rates over which nonequatorial ignition occurs is an increasing function of the neutron star spin frequency. These findings have significant implications for thermonuclear flame propagation, and they may explain why oscillations during the burst rise are detected predominantly when the accretion rate is high. They also support the suggestion of Bhattacharyya & Strohmayer that non-photospheric radius expansion double-peaked bursts and the unusual harmonic content of oscillations during the rise of some bursts result from ignition at or near a rotational pole.

4 pages, 2 figures, accepted by ApJL

References in corpus (2)

• Signature of Temporary Burning Front Stalling from a Non-Photospheric Radius Expansion Double-peaked Burst
• Spreading of thermonuclear flames on the neutron star in SAX J1808.4-3658: an observational tool

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• Coherence of burst oscillations and accretion-powered pulsations in the accreting millisecond pulsar XTE J1814-338
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• Thermonuclear X-ray bursts from LMXB 4U 1636$-$536 observed with AstroSat
• Accretion rate and the occurrence of multi-peaked X-ray bursts
• Nuclear-powered X-ray millisecond pulsars
• Phase-resolved analyses of mHz quasi-periodic oscillations in 4U 1636-53 using Hilbert-Huang transform
• Discovery of Thermonuclear Type-I X-ray Bursts from the X-ray binary MAXI J1807+132
• The study of multi-peaked type-I X-ray bursts in the neutron-star low mass X-ray binary 4U 1636$-$536 with RXTE
• X-ray burst ignition location on the surface of accreting X-ray pulsars: Can bursts preferentially ignite at the hotspot?
• 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
• Damping of Type I X-ray Burst Oscillations by Convection
• A solution to the tension of burning on neutron stars and nuclear physics
• Time and energy dependent characteristics of Thermonuclear burst oscillations