标题： 银河晕探索VI。 ：银河系内中央恒星晕中的盖亚恩克拉多斯/香肠RR兰娅星 显示英文标题

标题： The Galactic Bulge exploration VI.: Gaia Enceladus/Sausage RR Lyrae stars in the inner-central stellar halo of the Milky Way

摘要： 我们呈现了银河系内部中心区域（R <~ 10 kpc）的恒星晕视图，该区域由RR Lya星映射。结合BRAVA-RR/APOGEE RR Lya星目录，获得了一个位于银河系核球区域的281个RR Lya星样本，但它们的轨道表明它们属于内部中心晕。晕中的RR Lya星比核球中的RR Lya星更贫金属，并且脉动特性更符合吸积种群的特征。我们使用类似银河系的zoom-in宇宙学模拟Auriga，将RR Lya星的特性与“Gaia-Enceladus-Sausage”（GES）合并所预期的特性进行比较。RR Lya星的运动积分和偏心率与内部中心晕RR Lya星种群中6-9 +- 2%的小部分起源于GES一致。这个比例低于太阳邻域看到的比例，与Auriga模拟中观察到的趋势一致，在那里，类似于GES的合并在小银心半径处的GES恒星比例会比其他吸积种群更低。Auriga内部银河系GES-18粒子中很少有粒子的特性与具有（z_max < 1.1 kpc）核球种群一致，这表明没有（或非常少）具有核球轨道的RR Lya星应该起源于GES。 显示英文摘要

摘要： We present a view of the stellar halo in the inner-central regions of the Milky Way (R <~ 10 kpc) mapped by RR Lyrae stars. The combined BRAVA-RR/APOGEE RR Lyrae catalog is used to obtain a sample of 281 RR Lyrae stars located in the bulge region of the Galaxy, but with orbits indicating they belong to the inner-central halo. The RR Lyrae stars in the halo are more metal-poor than the bulge RR Lyrae stars and have pulsation properties more consistent with an accreted population. We use the Milky Way-like zoom-in cosmological simulation Auriga to compare the properties of the RR Lyrae stars to those expected from the "Gaia-Enceladus-Sausage" (GES) merger. The integrals of motions and eccentricities of the RR Lyrae stars are consistent with a small fraction of 6-9 +- 2 % of the inner-central halo RR Lyrae population having originated from GES. This fraction, lower than what is seen in the solar neighborhood, is consistent with trends seen in the Auriga simulation, where a GES-like merger would have a decreasing fraction of GES stars at small Galactocentric radii compared to other accreted populations. Very few of the Auriga inner Galaxy GES-18 particles have properties consistent with belonging to a bulge population with (z_max < 1.1 kpc), indicating that no (or very few) RR Lyrae stars with bulge orbits should have originated from GES.