论文标题
用距离梯度约束银河系卫星的形状
Constraining the shape of Milky Way satellites with distance gradients
论文作者
论文摘要
我们将深色能量摄像机遗产调查（贴花）与GAIA光度法结合在一起，以使用蓝色水平分支（BHB）恒星作为距离指示器研究引导I，Draco，Ursa Minor，Sextans，Sextans和Dwarf Galaxies的3D结构。我们构建了一个新的颜色 - 吸毒大小的BHB星星，用于测量矮星系体内的距离梯度。我们仅在二次和雕塑家中检测到具有统计学意义的非零梯度。通过三轴衰退模型对系统的梯度和2-D密度进行建模，我们发现两个矮星系中的距离梯度与扁平形状不一致，但与扁平或三方形状兼容。为了解释观察到的梯度，塞克斯人和雕塑家的模型需要具有大于塞克斯人大于0.47美元的固有椭圆形，雕刻家$ 0.46 $。扁平的扁平形状可能意味着速度分布的显着各向异性，以便与这些系统中缺乏明显的速度梯度一致。
We combine the Dark Energy Camera Legacy Survey (DECaLS) DR8 photometry with Gaia photometry to study the 3-D structure of Bootes I, Draco, Ursa Minor, Sextans and Sculptor dwarf galaxies using blue horizontal branch (BHB) stars as distance indicators. We construct a new colour-absolute magnitude of BHB stars that we use to measure the distance gradients within the body of the dwarf galaxies. We detect a statistically significant non-zero gradient only in Sextans and Sculptor. Through modeling of the gradient and 2-D density of the systems by triaxial Plummer models we find that the distance gradients in both dwarf galaxies are inconsistent with prolate shape, but compatible with oblate or triaxial shapes. In order to explain the observed gradients, oblate models of Sextans and Sculptor need to have a significant intrinsic ellipticity larger than $0.47$ for Sextans and $0.46$ for Sculptor. The flattened oblate shape may imply a significant anisotropy in velocity distribution in order to be consistent with the lack of significant velocity gradients in these systems.
