Title: Superburst oscillations: ocean and crustal modes excited by Carbon-triggered Type I X-ray bursts Show Chinese title

Title: 超级爆发振荡：由碳引发的I型X射线爆发激发的海洋和地壳模态

Abstract: Accreting neutron stars (NS) can exhibit high frequency modulations in their lightcurves during thermonuclear X-ray bursts, known as burst oscillations. The frequencies can be offset from the spin frequency of the NS by several Hz, and can drift by 1-3 Hz. One possible explanation is a mode in the bursting ocean, the frequency of which would decrease (in the rotating frame) as the burst cools, hence explaining the drifts. Most burst oscillations have been observed during H/He triggered bursts, however there has been one observation of oscillations during a superburst; hours' long Type I X-ray bursts caused by unstable carbon burning deeper in the ocean. This paper calculates the frequency evolution of an oceanic r-mode during a superburst. The rotating frame frequency varies during the burst from 4-14 Hz, and is sensitive to the background parameters, in particular the temperature of the ocean and ignition depth. This calculation is compared to the superburst oscillations observed on 4U-1636-536. The predicted mode frequencies ($\sim$ 10 Hz) would require a spin frequency of $\sim$ 592 Hz to match observations; 6 Hz higher than the spin inferred from an oceanic r-mode model for the H/He triggered burst oscillations. This model also over-predicts the frequency drift during the superburst by 90 %. Show Chinese abstract

Abstract: 吸积中子星（NS）在热核X射线爆发期间的光变曲线可能会表现出高频调制，称为爆发振荡。 这些频率可能偏离中子星的自转频率几个赫兹，并且可以漂移1到3赫兹。 一种可能的解释是在爆发海洋中的模式，其频率在冷却过程中（在旋转框架下）会降低，从而解释了漂移现象。 大多数爆发振荡是在H/He触发的爆发期间被观察到的，然而，在超长爆发期间也观察到了一次振荡；由深海中不稳定的碳燃烧引起的持续数小时的一型X射线爆发。 本文计算了超长爆发期间海洋r模式的频率演化。 旋转框架下的频率在整个爆发过程中从4到14赫兹变化，并且对背景参数敏感，尤其是海洋温度和点火深度。 这一计算与在4U-1636-536上观测到的超长爆发振荡进行了比较。 预测的模式频率（$\sim$ 10赫兹）需要一个自转频率为$\sim$ 592赫兹才能匹配观测结果；比通过H/He触发的爆发振荡的海洋r模式模型推断出的自转频率高6赫兹。 该模型还过高估计了超长爆发期间的频率漂移达90%。