We present a grid-based non-parametric approach to obtain a triaxial three-dimensional luminosity density from its surface brightness distribution. Triaxial deprojection is highly degenerate and our approach illustrates the resulting difficulties. Fortunately, for massive elliptical galaxies, many deprojections for a particular line of sight can be discarded, because their projection along other lines of sight does not resemble elliptical galaxies. The near-elliptical isophotes of these objects imply near ellipsoidal intrinsic shapes. In fact, deprojection is unique for densities distributed on ellipsoidal shells. The constrained non-parametric deprojection method we present here relaxes this constraint and assumes that the contours of the luminosity density are boxy/discy ellipsoids with radially varying axis ratios. With this approach we are able to reconstruct the intrinsic triaxial densities of our test models, including one drawn from an $N$-body simulation. The method also allows to compare the relative likelihood of deprojections at different viewing angles. We show that the viewing orientations of individual galaxies with nearly ellipsoidal isophotal shapes can be constrained from photometric data alone.
Triaxial Orbit-based Dynamical Modeling of Galaxies with Supermassive Black Holes and an Application to Massive Elliptical Galaxy NGC 1453
在轴对称假设下，利用轨道叠加技术得到了大部分邻近超大质量黑洞质量的恒星动力学测定。然而，很少有星系--特别是大质量的早期星系--遵守精确的轴对称。在这里，我们提出了一个修改后的轨道叠加代码和一个新的方法来动态确定的内在形状和质量参数的三轴星系的空间分辨恒星运动学数据的基础上。这里描述的三轴TriOS代码纠正了原始van den Bosch等人（2008年）代码中的一个错误，该错误导致三轴模型中大多数轨道的预测不正确，并可能显著影响参数碰撞参量。修订后的代码还包含轨道采样，质量约束和运行时间的显着改进。此外，我们引入了两个新的参数搜索策略-一组新的三轴形状参数和一种新的无网格采样技术-一起导致在定位最佳拟合模型的效率显着提高。我们将更新的代码和搜索方法应用于NGC 1453，一个快速旋转的大质量椭圆星系。完整的6D参数搜索找到固有轴比的$p=b/a=0.933^{+0.014}_{-0.015}$和$q=c/a=0.779\pm0.012$，以及三轴度参数的$T=0.33\pm0.06$。尽管偏离轴对称，最佳拟合SMBH质量，恒星质光比和NGC 1453的暗物质封闭质量与轴对称结果一致。在得出一般性结论之前，需要对轴对称和三轴模型进行更多的比较。
The Stellar IMF and Dark Matter Halo of ESO0286: Constraints from Strong Lensing and Dynamics
Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；Technical University of Munich（慕尼黑工业大学）；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理学研究所）；Université de Genève（日内瓦大学）；Institute of Cosmology and Gravitation, University of Portsmouth（朴茨茅斯宇宙学与引力研究所）
