Probing Neutron Star Superfluidity with Gravitational Wave Data

爱因斯坦的广义相对论预言了引力波的存在，引力波实际上是大质量物体振荡时产生的时空结构中的曲率涟漪。 引力波的最佳来源之一是中子星，它是超新星的残余物，当重恒星的核心在耗尽核燃料后坍塌时，会发生壮观的爆炸。 经过几个月的冷却，中子星星的核心预计将成为超流体，一种特殊的物质状态，可以没有摩擦地流动，只能通过形成一系列密集的超薄漩涡--非常薄的龙卷风--来旋转，这些漩涡穿过星星。 这个项目将开发基于计算机的超流中子星振荡及其发射的引力波模型，由于超流物质的特殊性质，超流中子星星的振荡模式应该与普通流体星星的振荡模式有很大不同。 因此，由振荡产生的引力波应该带有明显的超流性特征。 适当先进的引力波探测器应该能够从引力波数据中提取这种特征。 由于它们的极端质量（与太阳质量相当）和紧凑的尺寸（直径约20公里），中子星代表了一种无法在地球实验室中创造的物质形式。 引力波的直接探测使得中子星实际上成为研究极端条件下物质的天体物理实验室。

The Einstein theory of general relativity predicts the existence of gravitational waves, which are literally ripples of curvature in the fabric of space and time that are generated whenever massive objects oscillate. Among the best sources for gravitational waves are neutron stars, which are the remnants of supernovae, the spectacular explosions that result when the cores of heavy stars collapse after they have exhausted their nuclear fuel. After a few months of cooling, the core of a neutron star is predicted to become superfluid, a special state of matter that can flow with no friction and can rotate only by forming a dense array of Ultra-thin vortices --- very skinny tornados --- that thread the star. This project will develop computer-based models of the oscillations of superfluid neutron stars and the gravitational waves that they emit.Because of the special properties of superfluid matter, the modes of oscillation of a superfluid neutron star should be very different from those of an ordinary fluid star. Consequently, the gravitational waves that are created from their oscillations should carry a distinct signature of superfluidity. Suitably advanced gravitational wave detectors should be able to extract this signature from the gravitational wave data. Because of their extreme mass (on the order of the same mass as the Sun) and compact size (about 20 kilometers in diameter), neutron stars represent a form of matter that cannot be created in Earth-based laboratories. Direct detection of gravitational waves thus allows neutron stars to become, in effect, astrophysical laboratories for the study of matter under the most extreme conditions.