GLOBULAR CLUSTER STREAMS AS GALACTIC HIGH-PRECISION SCALES—THE POSTER CHILD PALOMAR 5
GLOBULAR CLUSTER STREAMS AS GALACTIC HIGH-PRECISION SCALES—THE POSTER CHILD PALOMAR 5
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DOI：
10.1088/0004-637x/803/2/80
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发表时间：
2015-02
期刊：
影响因子：
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通讯作者：
A. Küpper;E. Balbinot;A. Bonaca;K. Johnston;D. Hogg;P. Kroupa;B. Santiago
中科院分区：
文献类型：
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作者：
A. Küpper;E. Balbinot;A. Bonaca;K. Johnston;D. Hogg;P. Kroupa;B. Santiago
以银河系球状星团Palomar 5（105）的潮汐流为例，我们演示了如何有效地减少潮汐流的观测数据的维数，并在贝叶斯框架中建模。我们的方法结合检测流overdensities的差分高斯过程与快速条纹线模型的球状星团流和连续的似然函数从这些模型。用马尔可夫链蒙特卡罗法进行推理。通过生成107？>模型流，我们表明，独特的几何形状的2015碎片产生强大的约束太阳的位置和运动，银河系和2015本身。允许所有10个模型参数在大范围内变化，而无需额外的先验信息。仅使用现有的SDSS数据和文献中的一些径向速度，我们发现太阳到银河系中心的距离为8.30 ± 0.25 kpc，横向速度为253 ± 16 km s−1。这两个估计值与这两个量的独立测量值非常一致。采用标准的盘和球模型，我们计算出在19 kpc的远距星系半径范围内的银河系质量为（2.1 ± 0.4）× 10 11 M？> .此外，我们发现潜在的黑暗晕与平坦的q z = 0.95 - 0.12 + 0.16？>基本上是球形的-至少是在可被1005有效探测的径向范围内。我们还独立于其他方法确定了E105的质量、距离和自行，这使我们能够进行重要的交叉检查。我们推断的日心距离是23.6 − 0.7 + 0.8？kpc，在完美的协议，更精确的比，估计从深哈勃太空望远镜（HST）成像数据的等时线拟合。我们的结论是，发现和模拟更多的球状星团流是一种有效的方式来映射出我们的银河系的结构，以高精度。有了更多的观测数据，并通过使用额外的先验信息，这种映射的精度可以显着提高。
Using the example of the tidal stream of the Milky Way globular cluster Palomar 5 (Pal 5), we demonstrate how observational data on tidal streams can be efficiently reduced in dimensionality and modeled in a Bayesian framework. Our approach combines detection of stream overdensities by a Difference-of-Gaussians process with fast streakline models of globular cluster streams and a continuous likelihood function built from these models. Inference is performed with Markov chain Monte Carlo. By generating ≈ 10 7 ?> model streams, we show that the unique geometry of the Pal 5 debris yields powerful constraints on the solar position and motion, the Milky Way and Pal 5 itself. All 10 model parameters were allowed to vary over large ranges without additional prior information. Using only readily available SDSS data and a few radial velocities from the literature, we find that the distance of the Sun from the Galactic Center is 8.30 ± 0.25 kpc, and the transverse velocity is 253 ± 16 km s−1. Both estimates are in excellent agreement with independent measurements of these two quantities. Assuming a standard disk and bulge model, we determine the Galactic mass within Pal 5's apogalactic radius of 19 kpc to be ( 2.1 ± 0.4 ) × 10 11 M ⊙ ?> . Moreover, we find the potential of the dark halo with a flattening of q z = 0.95 − 0.12 + 0.16 ?> to be essentially spherical—at least within the radial range that is effectively probed by Pal 5. We also determine Pal 5's mass, distance, and proper motion independently from other methods, which enables us to perform vital cross-checks. Our inferred heliocentric distance of Pal 5 is 23.6 − 0.7 + 0.8 ?> kpc, in perfect agreement with, and more precise than, estimates from isochrone fitting of deep Hubble Space Telescope (HST) imaging data. We conclude that finding and modeling more globular cluster streams is an efficient way to map out the structure of our Galaxy to high precision. With more observational data and by using additional prior information, the precision of this mapping can be significantly increased.