论文标题
Meerkat-16 HI观察Dirr Galaxy WLM
MeerKAT-16 HI observation of the dIrr galaxy WLM
论文作者
论文摘要
我们介绍了运动学的观察和模型，以及在分离的矮人不规则星系中，中性氢（HI）的分布（HI）。我们与绿色银行望远镜（GBT）一起观察了WLM，也是Meerkat早期科学计划的一部分，那里有16盘可用。 WLM的HI光盘延伸至30 Arcmin（8.5 kpc）的主要轴直径，并且由GBT测量的次轴直径为20 Arcmin（5.6 kpc）。我们使用Meerkat数据使用Tirofific Software Suite对WLM进行建模，从而使我们能够拟合不同的倾斜型型号，并选择最匹配观察值的模型。我们的最终最佳拟合模型是扁平圆盘，具有垂直厚度，持续的倾斜度和分散，以及带有谐波扭曲的径向变化的表面亮度。为了模拟类似条形的运动，我们在切向方向和垂直方向的速度中包括二阶谐波畸变。我们提出了一个仅包含圆形运动的模型和一个具有非圆周运动的模型。后者更好地描述了数据。总体而言，模型重现了气体的全球分布和运动学，除了在2-sigma水平上有些微弱的发射。我们使用伪等温度（ISO）和Navarro-Frenk-White（NFW）暗物质晕模型对WLM的质量分布进行建模。 NFW和ISO模型符合形式错误的衍生旋转曲线，但是ISO模型可以更好地减小卡方值。 WLM中的质量分布在所有半径上都由暗物质主导。
We present observations and models of the kinematics and the distribution of the neutral hydrogen (HI) in the isolated dwarf irregular galaxy, Wolf-Lundmark-Melotte (WLM). We observed WLM with the Green Bank Telescope (GBT) and as part of the MeerKAT Early Science Programme, where 16 dishes were available. The HI disc of WLM extends out to a major axis diameter of 30 arcmin (8.5 kpc), and a minor axis diameter of 20 arcmin (5.6 kpc) as measured by the GBT. We use the MeerKAT data to model WLM using the TiRiFiC software suite, allowing us to fit different tilted-ring models and select the one that best matches the observation. Our final best-fitting model is a flat disc with a vertical thickness, a constant inclination and dispersion, and a radially-varying surface brightness with harmonic distortions. To simulate bar-like motions, we include second-order harmonic distortions in velocity in the tangential and the vertical directions. We present a model with only circular motions included and a model with non-circular motions. The latter describes the data better. Overall, the models reproduce the global distribution and the kinematics of the gas, except for some faint emission at the 2-sigma level. We model the mass distribution of WLM with a pseudo-isothermal (ISO) and a Navarro-Frenk-White (NFW) dark matter halo models. The NFW and the ISO models fit the derived rotation curves within the formal errors, but with the ISO model giving better reduced chi-square values. The mass distribution in WLM is dominated by dark matter at all radii.
