论文标题
用MIRA变量分析凸起的结构
Analysing the structure of the bulge with Mira variables
论文作者
论文摘要
据称，纬度为4 <| $ <10 $的银河凸起$ 4 <| b | $（deg。）$ <10 $显示X形，这意味着沿着视线的恒星密度分布具有双峰。但是，只有在红肥大的种群中观察到这个双峰，并且对其用作完美的标准蜡烛的疑问。我们旨在限制利用不同种群的凸起的形状：新的光学引力透镜实验数据发布Ogle-IV的MIRA变量，平均年龄为9 GYR。我们分析了远离平面的凸起区域，在那里我们将Miras的密度与宽大的凸起和X形凸起模型拟合在一起，并计算了每个模型的概率。我们发现，拟合数据的方形凸起的概率为$ p = 0.19 $，而X形凸起的概率仅为$ p = 2.85 \ cdot 10^{ - 6} $（等同于模型的张力，具有4.7 $σ$级别的数据）。因此，尽管我们不能完全确定地排除任何模型，但Boxy Bulge模型似乎更适合描述银河凸起。
The Galactic bulge at latitude $4<|b|$(deg.)$<10$ was claimed to show an X-shape, which means that stellar density distributions along the line of sight have a double peak. However, this double peak is only observed with the red-clump population, and doubt has been cast on its use as a perfect standard candle.\ As such, a boxy bulge without an X-shape is not discarded. We aim to constrain the shape of the bulge making use of a different population: Mira variables from the new Optical Gravitational Lensing Experiment data release, OGLE-IV, with an average age of 9 Gyr. We analysed an area of the bulge far from the plane, where we fitted the density of the Miras with boxy bulge and X-shaped bulge models and calculated the probability of each model. We find that the probability of a boxy bulge fitting the data is $p=0.19$, whereas the probability for the X-shaped bulge is only $p=2.85 \cdot 10^{-6}$ (equivalent to a tension of the model with the data of a 4.7$σ$ level). Therefore, the boxy bulge model seems to be more appropriate for describing the Galactic bulge, although we cannot exclude any model with complete certainty.
