论文标题

混乱中的外盘:用Gaia的星形样品对Monoceros和AC的盲目检测

The outer disc in shambles: blind detection of Monoceros and ACS with Gaia's astrometric sample

论文作者

Ramos, P., Antoja, T., Mateu, C., Anders, F., Laporte, C. F. P., Carballo-Bello, J. A., Famaey, B., Ibata, R.

论文摘要

Gaia的天体样品使我们能够研究最外面的银河盘,光环及其界面。正是在光盘的最边缘,外部扰动的效果预计最为明显。我们的目标是检测光环和银河盘边缘中存在的运动学子结构,并在其相空间分布上提供观察性约束。我们一次下载一个Healpix,是远处恒星的正确运动直方图,我们对其应用小波转换来揭示大量过度的过度。然后,我们分析出现在天空中的大型连贯结构。我们揭示了一个由monoceros(MNC)(MNC)和北部的Anterentre流(ACS)统治的尖锐而复杂的抗engentre,我们发现它们的强度与麦哲伦云和射手座流相当,而MNC South和MNC South和Triand则在负纬度上。我们的方法使我们能够对MNC和ACS进行形态学分析,均超过100 $^\ Circ $经度,并提供高纯度巨人样本,我们将MNC跟踪到低至$ \ sim $ 5 $^\ circ $的纬度。它们的颜色 - 磁性图与$ \ sim $ 10-11 kpc的扩展结构保持一致,该二键起源于圆盘,RR Lyrae与M巨人的比率非常低,并且在这些距离或仅较慢的距离时与旋转曲线兼容。我们提出了MNC和ACS的精确表征,这是我们方法自然揭示的两个先前已知的结构,使我们能够检测它们而不将自己限制为特定的恒星类型,并且首次仅使用运动学。我们的结果使未来的研究能够对其化学动力学和进化进行建模,从而限制了塑造MW的一些最具影响力的过程。

The astrometric sample of Gaia allows us to study the outermost Galactic disc, the halo and their interface. It is precisely at the very edge of the disc where the effects of external perturbations are expected to be the most noticeable. Our goal is to detect the kinematic substructure present in the halo and at the edge of the Milky Way (MW) disc, and provide observational constraints on their phase-space distribution. We download, one HEALpix at a time, the proper motion histogram of distant stars, to which we apply a Wavelet Transformation to reveal the significant overdensities. We then analyse the large coherent structures that appear in the sky. We reveal a sharp yet complex anticentre dominated by Monoceros (MNC) and the Anticentre Stream (ACS) in the north, which we find with an intensity comparable to the Magellanic clouds and the Sagittarius stream, and by MNC south and TriAnd at negative latitudes. Our method allows us to perform a morphological analysis of MNC and ACS, both spanning more than 100$^\circ$ in longitude, and to provide a high purity sample of giants with which we track MNC down to latitudes as low as $\sim$5$^\circ$. Their colour-magnitude diagram is consistent with extended structures at a distance of $\sim$10-11 kpc originated in the disc, with a very low ratio of RR Lyrae over M giants, and kinematics compatible with the rotation curve at those distances or only slightly slower. We present a precise characterisation of MNC and ACS, two previously known structures that our method reveals naturally, allowing us to detect them without limiting ourselves to a particular stellar type and, for the first time, using only kinematics. Our results allow future studies to model their chemo-dynamics and evolution, thus constraining some of the most influential processes that shaped the MW.

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源