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arXiv 2009.08979astro-ph.GA
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SMART:三轴星系Schwarzschild轨道叠加技术的新实现及其在N体合并模拟中的应用

SMART: A new implementation of Schwarzschild's Orbit Superposition technique for triaxial galaxies and its application to an N-body merger simulation

Bianca Neureiter, Jens Thomas, Roberto Saglia, Ralf Bender, Fabrizio Finozzi, Aliaksei Krukau, Thorsten Naab, Antti Rantala, Matteo Frigo

摘要:

我们提出了SMART,一个新的三维实现的史瓦西方法和它的应用三轴N体合并模拟。SMART拟合全视线速度分布(LOSVD),以确定视角,黑洞,恒星和暗物质(DM)的质量和星系的恒星轨道分布。我们的模型使用一个5D的轨道起始空间,以确保一组代表性的恒星轨迹适应运动积分空间,它的目的是处理非参数恒星和DM密度。SMART的效率证明了一个现实的N体合并模拟,包括超大质量黑洞,我们从五个不同的投影模型的应用。当提供真实视角、3D恒星光度轮廓和归一化的DM晕时,我们可以(i)以~1%的精度再现内禀速度矩和各向异性轮廓,(ii)恢复黑洞质量、恒星质光比和DM归一化到优于百分之几的精度。这个精度小于目前讨论的初始恒星质量函数和黑洞尺度关系中散射之间的差异。玩具模型的进一步测试表明,恢复的各向异性在三轴星系几乎是唯一的潜力是已知的,并充分LOSVD拟合。我们发现,轨道模型甚至允许重建完整的固有速度分布,其中包含更多的信息比经典的各向异性参数。令人惊讶的是,分析N体模拟的引力势的轨道库包含围绕中间轴的净旋转轨道,该轨道在某些陀螺仪上是稳定的。

英文摘要:

We present SMART, a new 3D implementation of the Schwarzschild Method and its application to a triaxial N-body merger simulation. SMART fits full line-of-sight velocity distributions (LOSVDs) to determine the viewing angles, black hole, stellar and dark matter (DM) masses and the stellar orbit distribution of galaxies. Our model uses a 5D orbital starting space to ensure a representative set of stellar trajectories adaptable to the integrals-of-motion space and it is designed to deal with non-parametric stellar and DM densities. SMART's efficiency is demonstrated by application to a realistic N-body merger simulation including supermassive black holes which we model from five different projections. When providing the true viewing angles, 3D stellar luminosity profile and normalized DM halo, we can (i) reproduce the intrinsic velocity moments and anisotropy profile with a precision of ~1% and (ii) recover the black hole mass, stellar mass-to-light ratio and DM normalization to better than a few percent accuracy. This precision is smaller than the currently discussed differences between initial-stellar-mass functions and scatter in black hole scaling relations. Further tests with toy models suggest that the recovery of the anisotropy in triaxial galaxies is almost unique when the potential is known and full LOSVDs are fitted. We show that orbit models even allow the reconstruction of full intrinsic velocity distributions, which contain more information than the classical anisotropy parameter. Surprisingly, the orbit library for the analysed N-body simulation's gravitational potential contains orbits with net rotation around the intermediate axis that is stable over some Gyrs.

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