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arXiv 2603.01044astro-ph.GA
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银河系ESO 358-60的运动学与动力学

Kinematic and dynamics of the galaxy ESO 358-60

Centro Ricerche Enrico Fermi（恩里科·费米研究中心）；Istituto Nazionale Fisica Nucleare, Unità Roma 1, Dipartimento di Fisica, Universitá di Roma “Sapienza”（意大利国家核物理研究所罗马第一分部罗马大学物理系）；Sony CSL - Rome, Joint Initiative CREF-SONY, Centro Ricerche Enrico Fermi（索尼中央研究实验室罗马分部CREF-SONY联合倡议恩里科·费米研究中心）

Francesco Sylos Labini, Matteo Straccamore

备注：
17 pages, 11 figure, accepted for publication in The Astrophysical Journal
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AI总结：

通过比较VRM与TRM方法，研究ESO 358-60星系的运动学特征及质量分布，发现盘状结构与扭曲现象的差异，并评估不同质量模型的拟合效果。

摘要：

我们利用HI测量数据，采用速度环模型（VRM）方法研究不规则星系ESO 358-60的径向速度场。该技术假设存在一个共面的盘状结构，使我们能够从观测到的视线速度场中重建出径向和切向速度分量的粗粒度地图。这些地图显示，在内区切向运动占主导地位，而向外则径向运动逐渐变得显著。这种运动学行为与通过倾斜环模型（TRM）推断出的结果形成对比，后者表明中间盘区径向运动更为显著，而边缘区则几乎可以忽略，并检测到约20度的明显扭曲，内盘几乎面朝地球，外区则倾斜约60度。相比之下，VRM分析发现该盘在中心区域具有棒状结构。这一解释进一步得到了强度和速度分散地图的支持。为了测试TRM推导出的扭曲起源，我们基于TRM结果构建了一个玩具模型，并用VRM技术分析该模型，发现扭曲可能是由于TRM假设引起的伪影。最后，我们使用标准暗物质晕模型和暗物质盘（DMD）模型估算星系的质量，其中所有质量都位于盘面内。DMD模型得出的总质量大约低约三倍，并且对旋转曲线的拟合略好一些。

英文摘要：

We investigate the velocity field derived from HI measurements of the irregular galaxy ESO 358-60 using the Velocity Ring Model (VRM) method. This technique, which assumes a coplanar disk, allows us to reconstruct coarse-grained maps of both radial and tangential velocity components from the observed line-of-sight velocity field. Such maps reveal that tangential motions dominate the inner regions, while radial motions become increasingly significant toward the outskirts. This kinematic behavior contrasts with that inferred from the Tilted Ring Model (TRM), which suggests that radial motions are more prominent in the intermediate disk and negligible in the outskirts and detects a pronounced warp of approximately $20^\circ$, with the inner disk nearly edge-on and the outer regions inclined by approximately $60^\circ$. In contrast, the VRM analysis finds that the disk exhibits a bar-like structure in its central regions. This interpretation is further supported by the intensity and velocity dispersion maps. To test the origin of the TRM-derived warp, we construct a toy model based on the TRM results and analyze it with the VRM technique, finding evidence that the warp is likely an artifact arising from the TRM's assumptions. Finally, we estimate the galaxy's mass using both the standard dark matter halo model and a dark matter disk (DMD) model, where all mass lies in the disk plane. The DMD yields a total mass approximately three times lower and provides a slightly better fit to the rotation curve.

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