狮子座I的解剖学：潮汐尾如何影响运动学
The anatomy of Leo I: how tidal tails affect the kinematics
摘要：
我们最近发表的狮子座I dSph星系的运动学数据集，通过拟合的Jeans方程的解的速度色散和峰度的数据测量的配置文件。我们证明，当样本是清洁的闯入者的数据是一致的假设，质量遵循轻和各向同性的恒星轨道，不需要扩展的暗物质晕。正如Leo I的旋转曲线所证明的那样，我们的干扰者去除方案并没有完全清除污染数据。当远离矮星中心时，旋转似乎是反向的。我们解释这种行为使用的N-体模拟的矮星系具有一些内在的旋转，在银河系的潜力和轨道运行的结果表明，它可以复制，如果星系几乎是沿着潮汐尾巴，使领先的（背景）尾巴污染狮子座I的西部，而尾部（前景）尾巴的东部。我们表明，这种配置导致视线速度的对称和高斯分布。模拟也适用于模拟数据集上测试我们的建模方法。我们证明，当数据被清除的闯入者和第四速度矩是使用的侏儒的真实参数通常是在1 σ误差的最佳拟合参数。将拟合限制在狮子座I的内部，我们对各向异性的最佳估计是β=-0.2 ^{+0.3}_{-0.4}，总质量M =（4.5 +/- 0.7）x 10^7 M_sun。计算了质量、亮度和距离误差的质光比为M/L_V = 8.2 +/-4.5太阳单位。
英文摘要：
We model the recently published kinematic data set for Leo I dSph galaxy by fitting the solutions of the Jeans equations to the velocity dispersion and kurtosis profiles measured from the data. We demonstrate that when the sample is cleaned of interlopers the data are consistent with the assumption that mass follows light and isotropic stellar orbits with no need for an extended dark matter halo. Our interloper removal scheme does not clean the data of contamination completely, as demonstrated by the rotation curve of Leo I. When moving away from the centre of the dwarf, the rotation appears to be reversed. We interpret this behaviour using the results of an N-body simulation of a dwarf galaxy possessing some intrinsic rotation, orbiting in the Milky Way potential and show that it can be reproduced if the galaxy is viewed almost along the tidal tails so that the leading (background) tail contaminates the western part of Leo I while the trailing (foreground) tail the eastern one. We show that this configuration leads to a symmetric and Gaussian distribution of line-of-sight velocities. The simulation is also applied to test our modelling method on mock data sets. We demonstrate that when the data are cleaned of interlopers and the fourth velocity moment is used the true parameters of the dwarf are typically within 1 σerrors of the best-fitting parameters. Restricting the fitting to the inner part of Leo I our best estimate for the anisotropy is β= -0.2^{+0.3}_{-0.4} and the total mass M = (4.5 +/- 0.7) x 10^7 M_sun. The mass-to-light ratio including the errors in mass, brightness and distance is M/L_V = 8.2 +/- 4.5 solar units.
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