Studies of the red clump giant population in the inner Milky Way suggest the Galactic bulge/bar has a boxy/peanut/X-shaped structure as predicted by its formation via a disc buckling instability. We used a non-parametric method of estimating the Galactic bulge morphology that is based on maximum entropy regularisation. This enabled us to extract the three-dimensional distribution of the red giant stars in the bulge from deep photometric catalogues of the VISTA Variables in the Via Lactea (VVV) survey. Our high-resolution reconstruction confirms the well-known boxy/peanut/X-shaped structure of the bulge. We also find spiral arm structures that extend to around three kpc in front of and behind the bulge and are on different sides of the bulge major axis. We show that the detection of these structures is robust to the uncertainties in the luminosity function.

中文翻译：

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在 VVV 巡天中使用红团星对银河凸起区域进行非参数密度重建

对银河系内部红团巨星种群的研究表明，银河系凸起/棒具有四四方方/花生/X 形结构，正如其通过盘屈曲不稳定性形成所预测的那样。我们使用了一种非参数方法来估计基于最大熵正则化的银河膨胀形态。这使我们能够从 Via Lactea (VVV) 巡天中 VISTA 变量的深光度目录中提取红巨星在凸起中的三维分布。我们的高分辨率重建证实了众所周知的四四方方/花生/X 形结构的凸起。我们还发现螺旋臂结构在凸起前后延伸到大约 3 kpc，并且位于凸起主轴的不同侧。