论文标题
由于X射线爆发引起的辐射驱动的积聚盘翘曲
Radiation Driven Warping of Accretion Discs Due to X-ray Bursts
论文作者
论文摘要
X射线爆发过程中辐射的倾泻会影响中子恒星周围积聚盘的特性：电晕可以冷却并塌陷，由于增强的积聚，可以将内部区域擦掉，并且额外的加热将导致圆盘高度的变化。在本文中，我们研究了爆发的辐射是否会导致光盘通过翘曲的不稳定性扭曲。在各向同性粘度和线性生长的极限下工作，我们发现，当圆盘具有较大的亮度和更长的持续时间时，爆发更有可能驱动椎间盘的扭曲。因此，在中间持续时间爆发（IMDB）和超级爆炸期间，扭曲最有可能是光谱半径扩展的证据。此外，扭曲的发展取决于盘式粘度，较大的$α$的值增加了经翘曲生长的可能性。我们对I型爆发和IMDB期间的WARPS开发进行时间依赖性演化计算。根据爆发前的初始翘曲，我们发现爆发的损失$ r $ <〜50 $ r_g $，在第二长时间尺度上迅速增长和衰减，或者在较慢的时间内生长并覆盖大部分光盘。在小半径上的经线脉动似乎具有解释某些IMDB尾巴期间观察到的可观波动所需的特性。大规模，缓慢生长的扭曲可以解释4U 1820-30和4U 1636-53超级爆炸的巨大反射强度和吸收柱密度。
The outpouring of radiation during an X-ray burst can affect the properties of accretion discs around neutron stars: the corona can cool and collapse, the inner regions can be bled away due to enhanced accretion, and the additional heating will lead to changes in the disc height. In this paper, we investigate whether radiation from bursts can cause the disc to distort through a warping instability. Working in the limit of isotropic viscosity and linear growth, we find that bursts are more likely to drive disc warps when they have larger luminosities and longer durations. Therefore, warps will be most probable during intermediate duration bursts (IMDBs) and superbursts with evidence for photospheric radius expansion. Further, the development of warps depends on the disc viscosity with larger values of $α$ increasing the likelihood of warp growth. We perform time-dependent evolution calculations of the development of warps during Type I bursts and IMDBs. Depending on the initial warp prior to the burst, we find the burst produces warps at $r$ <~ 50 $r_g$ that rapidly grow and decay on second-long timescales, or ones that grow more slowly and cover a large fraction of the disc. The pulsations of warp at small radii appear to have the properties needed to explain the achromatic fluctuations that have been observed during the tails of some IMDBs. The large scale, slowly growing warps could account for the large reflection strengths and absorbing column densities inferred late in the 4U 1820-30 and 4U 1636-53 superbursts.
