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arXiv 2003.05561astro-ph.GA
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通过人口轨道叠加解开星系的形成历史:方法验证

Disentangling the formation history of galaxies via population-orbit superposition: method validation

Ling Zhu, Glenn van de Ven, Ryan Leaman, Robert J. J. Grand, Jesus Falcon-Barroso, Prashin Jethwa, Laura L. Watkins, Shude Mao, Adriano Poci, Richard M. McDermi… 展开作者

Ling Zhu, Glenn van de Ven, Ryan Leaman, Robert J. J. Grand, Jesus Falcon-Barroso, Prashin Jethwa, Laura L. Watkins, Shude Mao, Adriano Poci, Richard M. McDermid, Dandan Xu, Dylan Nelson

摘要:

我们提出了人口轨道叠加模型的基础上史瓦西的轨道叠加方法,通过标记的轨道年龄和金属丰度的外部星系。该模型适合的密度分布,以及运动学,年龄和金属丰度图从积分场单元(IFU)光谱观测。我们验证了该方法,并证明了它的权力,通过将其应用到模拟数据,类似于那些获得的多单元光谱探测器(MUSE)的使用说明书上的甚大望远镜(VLT)。这些模拟数据是从御夫座星系模拟创建的,在三个不同的倾角($\vartheta=40^o, 60^o, 80^o$)。在MUSE-like模拟数据的约束下,我们的模型可以恢复星系轨道圆度$λ_z$与半径$r$的投影分布,年龄$t$与金属度$Z$的内禀恒星星族分布,以及轨道圆度$λ_z$与恒星年龄$t$之间的相关性.一个物理动机的年龄-金属丰度关系改善恢复本征恒星星族分布。我们根据星系轨道圆度分布将星系分解为冷、暖和热+反旋分量,发现我们模型中每个分量的面密度、平均速度、速度色散、年龄和金属丰度图都很好地再现了模拟结果,特别是在边缘投影附近,这些星系表现出很强的全球年龄与$σ_z$的关系,我们的模型很好地恢复了这一关系.该方法有能力揭示星系中恒星结构的详细建立,并为星系演化的局部分辨和高红移研究提供了补充。

英文摘要:

We present population-orbit superposition models for external galaxies based on Schwarzschild's orbit-superposition method, by tagging the orbits with age and metallicity. The models fit the density distributions, as well as kinematic, age and metallicity maps from Integral Field Unit (IFU) spectroscopy observations. We validate the method and demonstrate its power by applying it to mock data, similar to those obtained by the Multi-Unit Spectroscopic Explorer (MUSE) IFU on the Very Large Telescope (VLT). These mock data are created from Auriga galaxy simulations, viewed at three different inclination angles ($\vartheta=40^o, 60^o, 80^o$). Constrained by MUSE-like mock data, our model can recover the galaxy's stellar orbit distribution projected in orbital circularity $λ_z$ vs. radius $r$, the intrinsic stellar population distribution in age $t$ vs. metallicity $Z$, and the correlation between orbits' circularity $λ_z$ and stellar age $t$. A physically motivated age-metallicity relation improves recovering the intrinsic stellar population distributions. We decompose galaxies into cold, warm and hot + counter-rotating components based on their orbit circularity distribution, and find that the surface density, mean velocity, velocity dispersion, age and metallicity maps of each component from our models well reproduce those from simulation, especially for projections close to edge-on. These galaxies exhibit strong global age vs. $σ_z$ relation, which is well recovered by our model. The method has the power to reveal the detailed build-up of stellar structures in galaxies, and offers a complement to local resolved, and high-redshift studies of galaxy evolution.

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