Tidal disruptions of white dwarfs as probes for intermediate mass black holes in globular clusters

一些球状星团中存在中等质量黑洞(IMBH)的证据已经积累起来。当恒星在星团中扩散时，一些恒星将不可避免地在距离黑洞足够近的地方徘徊，从而遭受潮汐破坏。IMBH假说的一个吸引人的特点是，它不仅有可能扰乱太阳型恒星，还可能扰乱致密的白矮星。我们最近调查了接近黑洞的白矮星的命运，这些黑洞被破坏和压缩到足以引发爆炸性核燃烧的程度。我们发现，热核点火是所有质量的白矮星在潮汐半径范围内通过的自然结果。如果探测到一次特殊的低光热核爆炸，并伴随着软X射线瞬变信号，将是IMBH存在的令人信服的证据。这些以前的计算是基于使用相对论赝势。在这个方案中，我们建议在一个固定的黑洞背景度规上用相对论的方法来研究黑洞的破裂过程。具体目标是将相对论重力和流体力学应用到当前的流体力学+核网络模型中。使用这个工具，我们将研究特别近距离的碰撞，其中强烈的重力效应是重要的，无论是旋转的黑洞还是非旋转的黑洞。

Suggestive evidence has accumulated that intermediate mass black holes (IMBHs) exist in some globular clusters. As stars diffuse in the cluster, some will inevitably wander sufficiently close to the hole that they suffer a tidal disruption. An attractive feature of the IMBH hypothesis is its potential to disrupt not only solar-type stars but also compact white dwarf stars. We have recently investigated the fate of white dwarfs that approach the hole close enough to be disrupted and compressed to such an extent that explosive nuclear burning is triggered. We found that thermonuclear ignition is a natural outcome for white dwarfs of all masses passing well within the tidal radius. A peculiar, underluminous thermonuclear explosion accompanied by a soft X-ray transient signal would, if detected, be a compelling testimony for the presence of an IMBH.These previous calculations were based on the use of a relativistic pseudo-potential. In this proposal we suggest to explore the disruption process in a relativistic approach on a fixed black hole background metric. The specific goal is to implement relativistic gravity and hydrodynamics into the current hydrodynamics plus nuclear network model. Using this tool we will study particularly close encounters where strong gravity effects are important, both with rotating and non-rotating black holes.