The manifestations of thermal instabilities in accretion discs

吸积盘存在于大量的天体物理环境中。当物质在重力作用下落向一个中心，通常是致密的物体时，它们就形成了。由于物质中的角动量，它在中心物体周围形成一个圆盘。圆盘中的粘性力导致材料向内移动并附着在中心物体上。这些圆盘的简化分析理论表明，它们应该对热波动不稳定(即它们应该灾难性地变热或变冷)。在观察中没有迹象表明这种情况在自然界中发生，其原因仍然很难理解。我们的目标是探索这个问题，从涉及随机过程的简化分析理论的扩展开始。我们的最终计划是构建大规模的计算机模拟，使我们能够详细研究这些现象(或缺乏这些现象)。

Accretion discs are found in a large number of astrophysical situations. They form when matter falls under gravity towards a central, often compact, body. Due to angular momentum in the material, it settles into a disc around the central body. Viscous forces in the disc cause material to move inwards and accrete onto the central object.A simplified analytical theory of these discs suggests that they should be unstable to thermal fluctuations (ie they should catastrophically heat or cool). There is no indication in observations that this happens in nature, and the reason for this is still poorly understood.We aim to explore this problem, starting with extensions to the simplified analytical theory involving stochastic processes. Our eventual plan is to construct large scale computer simulations which will enable us to study these phenomena (or lack thereof) in detail.