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arXiv 1709.06649astro-ph.GA
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CALIFA旋涡星系的轨道分解

Orbital decomposition of CALIFA spiral galaxies

Ling Zhu, Remco van den Bosch, Glenn van de Ven, Mariya Lyubenova, Jesús Falcón-Barroso, Sharon E. Meidt, Marie Martig, Juntai Shen, Zhao-Yu Li, Akin Yildirim, … 展开作者

Ling Zhu, Remco van den Bosch, Glenn van de Ven, Mariya Lyubenova, Jesús Falcón-Barroso, Sharon E. Meidt, Marie Martig, Juntai Shen, Zhao-Yu Li, Akin Yildirim, C. Jakob Walcher, Sebastian F. Sanchez

摘要:

基于史瓦西轨道的动力学模型被广泛用于揭示早型星系和球状星团的内部动力学。在这里,我们提出了第一次晚型星系的史瓦西模型:SBb星系NGC 4210和S0星系NGC 6278从CALIFA调查。$2\,R_e$内的质量分布受到$1σ$统计误差$\sim 10\%$的良好约束。在不确定度分别为$\sim 20\%$和$\sim 50\%$的情况下,可以将亮质量和暗质量解纠缠。从$R_e$到$2\,R_e$,NGC 4210的暗物质分数从$14\pm10\%$增加到$18\pm10\%$,NGC 6278的暗物质分数从$15\pm10\%$增加到$30\pm20\%$。$σ_r/σ_t$和$σ_z/σ_R$的速度各向异性剖面都受到很好的约束。推断的内部轨道分布揭示了清晰的亚结构。轨道自然地分为三个部分:一个接近圆形轨道的冷部分,一个接近径向轨道的热部分,以及一个介于两者之间的暖部分。光度测定法确定的指数盘主要由仅在$\sim 1\,R_e$之外的冷轨道组成,而它们主要由内部的温暖轨道构成。我们的动力学热分量集中在内部区域,类似于光度测定确定的凸起。通过模拟数据验证了模型计算结果的可靠性,特别是轨道分布的可靠性。

英文摘要:

Schwarzschild orbit-based dynamical models are widely used to uncover the internal dynamics of early-type galaxies and globular clusters. Here we present for the first time the Schwarzschild models of late-type galaxies: an SBb galaxy NGC 4210 and an S0 galaxy NGC 6278 from the CALIFA survey. The mass profiles within $2\,R_e$ are constrained well with $1σ$ statistical error of $\sim 10\%$. The luminous and dark mass can be disentangled with uncertainties of $\sim 20\%$ and $\sim 50\%$ respectively. From $R_e$ to $2\,R_e$, the dark matter fraction increases from $14\pm10\%$ to $18\pm10\%$ for NGC 4210 and from $15\pm10\%$ to $30\pm20\%$ for NGC 6278. The velocity anisotropy profiles of both $σ_r/σ_t$ and $σ_z/σ_R$ are well constrained. The inferred internal orbital distributions reveal clear substructures. The orbits are naturally separated into three components: a cold component with near circular orbits, a hot component with near radial orbits, and a warm component in between. The photometrically-identified exponential disks are predominantly made up of cold orbits only beyond $\sim 1\,R_e$, while they are constructed mainly with the warm orbits inside. Our dynamical hot components are concentrated in the inner regions, similar to the photometrically-identified bulges. The reliability of the results, especially the orbit distribution, are verified by applying the model to mock data.

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