论文标题
检测使用潮汐流的暗物质光环的数字旋转
Detecting the Figure Rotation of Dark Matter Halos with Tidal Streams
论文作者
论文摘要
宇宙学模拟中围绕银河系状星系的暗物质光环是一级三轴的。大约30年前，人们预测这种三轴暗物质光环应在几个吉维（Gigayears）的持续时间内表现出稳定的数字旋转或翻滚运动。通过宇宙学模拟预测的图形旋转的角频率通过模式速度的对数正态分布描述，中位值0.15hkm/s/kpc（〜0.15h rad/gyr/gyr〜9h deg/gyr）和0.83km/s/kpc的宽度。这些图案速度是如此之小，以至于它们通常被认为既不重要又无法发现。在这项工作中，我们表明，即使是这种极慢的数字旋转，也可以显着改变由银河系中卫星的潮汐破坏产生的扩展恒星流的结构。当在三个主轴周围旋转光环时，我们模拟了射手座状的极地潮流流的行为，其形状不同。对于典型的宇宙学光环的模式速度，我们首次证明了类似射手座的潮汐流，即使在当前观察结果中也可以检测到可以检测到的程度。这一发现可能会允许对银河系深色光环的数字旋转进行未来的测量，也许可以证明这种相对未开发的LambDACDM预测。
The dark matter halos that surround Milky Way-like galaxies in cosmological simulations are, to first order, triaxial. Nearly 30 years ago it was predicted that such triaxial dark matter halos should exhibit steady figure rotation or tumbling motions for durations of several gigayears. The angular frequency of figure rotation predicted by cosmological simulations is described by a log-normal distribution of pattern speed with a median value 0.15hkm/s/kpc (~ 0.15h rad/Gyr ~ 9h deg/Gyr) and a width of 0.83km/s/kpc. These pattern speeds are so small that they have generally been considered both unimportant and undetectable. In this work we show that even this extremely slow figure rotation can significantly alter the structure of extended stellar streams produced by the tidal disruption of satellites in the Milky Way halo. We simulate the behavior of a Sagittarius-like polar tidal stream in triaxial dark matter halos with different shapes, when the halos are rotated about the three principal axes. For pattern speeds typical of cosmological halos we demonstrate, for the first time, that a Sagittarius-like tidal stream would be altered to a degree that is detectable even with current observations. This discovery will potentially allow for a future measurement of figure rotation of the Milky Way's dark halo, and perhaps enabling the first evidence of this relatively unexplored prediction of LambdaCDM.
