论文标题
超透明星系的恒星光盘有多“冷”？
How "cold" are the stellar discs of superthin galaxies?
论文作者
论文摘要
超透明星系是一类无块状的低表面亮度星系，具有惊人的平面与垂直轴比率$ \ rm（b/a> 10-20）$，可能表明存在超冷的恒星光盘。使用暗物质光环的力场以及恒星动力代码Agama（基于动作的星系建模架构）的重力耦合恒星和气体的多组分银河盘模型，我们确定恒星和气体的垂直速度分散恒星和气体作为五个超级半径的Galacto中心半径（UGC 7349）的函数IC2233和UGC00711）使用Markov Chain Monte Carlo方法，使用观察到的恒星和原子氢（HI）尺度作为约束。我们发现，光带中恒星光盘的主要垂直速度分散在$σ_{0S} $ $ \ sim $ \ sim $ 10.2-10.2-18.4 $ $ \ rm {kms}^kms}^{ - 1} $中，跌落，跌落的比例为$ 2.6 $ 2.6 $ $ 3.2 $ $ r _ $ r _ $ r _;恒星圆盘比例长度。有趣的是，在3.6 $μ$ m的情况下，在恒星盘的两个组件上平均，在$ 5.9 $到$ 11.8 $ $ \ $ \ rm {kms}^{ - 1} $之间，这两者都证实了“ Ultra ultra-cold”的出现在超级the素星座中。有趣的是，我们的样品超级thins的多组分光盘动力学稳定性参数$ q_n $的全局中位数为5 $ \ pm $ 1.5，高于螺旋星系样本的全球中值2.2 $ \ pm 0.6 $ 0.6。
Superthin galaxies are a class of bulgeless, low surface brightness galaxies with strikingly high values of planar-to-vertical axes ratio $\rm(b/a> 10 - 20)$, possibly indicating the presence of an ultra-cold stellar disc. Using the multi-component galactic disc model of gravitationally-coupled stars and gas in the force field of the dark matter halo as well as the stellar dynamical code AGAMA (Action-based Galaxy Modelling Architecture), we determine the vertical velocity dispersion of stars and gas as a function of galacto-centric radius for five superthin galaxies (UGC 7321, IC 5249, FGC 1540, IC2233 and UGC00711) using observed stellar and atomic hydrogen (HI) scale heights as constraints, using a Markov Chain Monte Carlo Method. We find that the central vertical velocity dispersion for the stellar disc in the optical band varies between $σ_{0s}$ $\sim$ $10.2 - 18.4$ $\rm{kms}^{-1}$ and falls off with an exponential scale length of $2.6$ to $3.2$ $R_{d}$ where $R_{d}$ is the exponential stellar disc scale length. Interestingly, in the 3.6 $μ$m, the same, averaged over the two components of the stellar disc, varies between $5.9$ to $11.8$ $\rm{kms}^{-1}$, both of which confirm the presence of "ultra-cold" stellar discs in superthin galaxies. Interestingly, the global median of the multi-component disc dynamical stability parameter $Q_N$ of our sample superthins is found to be 5 $\pm$ 1.5, which higher than the global median value of 2.2 $\pm$ 0.6 for a sample of spiral galaxies.
