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arXiv · 1811.12111

Burning in the tail: implications for a burst oscillation model

Frank R. N. Chambers·Anna L. Watts·L. Keek·Yuri Cavecchi·F. Garcia
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Abstract

Accreting neutron stars (NS) can exhibit high-frequency modulations, known as burst oscillations, in their lightcurves during thermonuclear X-ray bursts. Their frequencies can be offset from the spin frequency of the NS (known independently) by several Hz, and can drift by 1-3 Hz. One plausible explanation for this phenomenon is that a wave is present in the bursting ocean that decreases in frequency (in the rotating frame) as the burst cools. The strongest candidate is the buoyant $r$-mode; however, models for the burning ocean background used in previous studies over-predict frequency drifts by several Hz. Using new background models (which include shallow heating, and burning in the tail of the burst) the evolution of the buoyant $r$-mode is calculated. The resulting frequency drifts are smaller, in line with observations. This illustrates the importance of accounting for the detailed nuclear physics in these bursts.

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Frank R. N. Chambers, Anna L. Watts, L. Keek, Yuri Cavecchi, F. Garcia. 2018-11-29. Burning in the tail: implications for a burst oscillation model. https://doi.org/10.3847/1538-4357%2Faaf501

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