论文标题
带有Gaia-Dr2的外银盘的结构
Structure of the outer Galactic disc with Gaia-DR2
论文作者
论文摘要
目标。我们使用从Gaia DR2获得的星数到半乳缘距离r = 20 kpc，使用反视差误差的反卷积技术来计算恒星密度。然后，我们分析密度以研究外带圆盘的结构，主要是经线。 方法。为了进行反卷积，我们使用了露西倒置技术来恢复校正后的恒星计数。我们还使用了$ m_g <10 $的恒星的Gaia光度函数来从恒星计数中提取出色的密度。 结果。恒星密度图可以通过指数圆盘沿径向方向拟合，$ h_r = 2.07 \ pm0.07 $ kpc，对方位角的依赖较弱，最高为20 kpc，而无需任何截止。耀斑和翘曲清晰可见。对称S形经纱的最佳拟合给出$ z_w = z_ \ odot +（37 \ pm 4.2（stat。） - 0.91（syst。））$ pc $（r/r_ \ odot）^{2.42 \ pm 0.76（stat。 （SYST。））$用于整个人口。当我们分别分析北部和南部扭曲时，我们获得了北部$ \ sim25 \％$较大幅度的不对称性。该结果可能会受到灭绝的影响，因为Gaia G带很容易出现灭绝偏见。但是，我们测试了我们使用的灭绝图的准确性，这表明灭绝在外盘中很好地确定了。但是，我们记得我们不知道完整的灭绝错误，我们也不知道地图的系统错误，这可能会影响最终结果。 该分析也仅对非常发光的恒星（$ m_g <-2 $）进行，平均代表年轻人的人口。我们获得了类似的规模长度，而经纱的最大幅度为$ 20-30 \％$ $ $ $ $比整个人口大。维持南北的不对称性。
AIMS. We calculate the stellar density using star counts obtained from Gaia DR2 up to a Galactocentric distance R=20 kpc with a deconvolution technique for the parallax errors. Then we analyse the density in order to study the structure of the outer Galactic disc, mainly the warp. METHODS. In order to carry out the deconvolution, we used the Lucy inversion technique for recovering the corrected star counts. We also used the Gaia luminosity function of stars with $M_G<10$ to extract the stellar density from the star counts. RESULTS. The stellar density maps can be fitted by an exponential disc in the radial direction $h_r=2.07\pm0.07$ kpc, with a weak dependence on the azimuth, extended up to 20 kpc without any cut-off. The flare and warp are clearly visible. The best fit of a symmetrical S-shaped warp gives $z_w= z_\odot+(37\pm 4.2(stat.)-0.91(syst.))$ pc $(R/R_\odot )^{2.42\pm 0.76(stat.) + 0.129 (syst.)} sin(ϕ+9.3\pm 7.37 (stat.) +4.48 (syst.))$ for the whole population. When we analyse the northern and southern warps separately, we obtain an asymmetry of an $\sim25\%$ larger amplitude in the north. This result may be influenced by extinction because the Gaia G band is quite prone to extinction biases. However, we tested the accuracy of the extinction map we used, which shows that the extinction is determined very well in the outer disc. Nevertheless, we recall that we do not know the full extinction error, and neither do we know the systematic error of the map, which may influence the final result. The analysis was also carried out for very luminous stars alone ($M_G<-2$), which on average represents a younger population. We obtain similar scale-length values, while the maximum amplitude of the warp is $20-30\%$ larger than with the whole population. The north-south asymmetry is maintained.
