论文标题
高自旋温度在大冲击参数下：星系郊区的电离
High spin temperatures at large impact parameters: Ionisation in the outskirts of galaxies
论文作者
论文摘要
通过包括通过近乎银河系的HI 21-CM吸收的最新观察结果，我们证实了我们先前的断言，即凉爽的中性原子气和影响参数之间存在抗可相关性。将样品的中性氢柱密度与吸收强度进行比较，我们发现在〜14 kpc的冲击参数下，平均自旋温度的峰值峰值，其余磁盘的其余峰值> 1000 k。这与银河系中的自旋温度分布显着不同，后者在8-25 kpc上表现出〜250-400 k的常数。但是，测得的色谱柱密度可能会受到束稀释的影响，我们表明，观察到HI 21-cm发射的情况似乎是这种情况，在该观察中，梁将半径降低了> 10 kpc。因此，除样品的平均值外，我们还应用了银河系的色谱柱密度曲线，在足够高的分辨率下观察到，在Illustristng模拟中近距离的星系的平均曲线。所有模型在相似的半径/冲击参数下（10-15 kpc）作为测量的柱密度在平均自旋温度中产生峰值。这些半径与HII区域通常集中的螺旋臂相似。因此，我们建议升高的自旋温度追踪在许多螺旋星系的外盘中观察到的HII区域。
By including the most recent observations of HI 21-cm absorption through near-by galactic disks, we confirm our previous assertion that there is an anti-correlation between the abundance of cool neutral atomic gas and impact parameter. Comparing the measured neutral hydrogen column densities of the sample with the absorption strength, we find a peak in the mean spin temperature of ~2310 K at an impact parameter of ~ 14 kpc, with > 1000 K in the remainder of the disk. This is significantly different to the spin temperature distribution in the Milky Way, which exhibits a constant ~ 250 - 400 K over 8 - 25 kpc. The measured column densities may, however, suffer from beam dilution, which we show appears to be the case for the observations of HI 21-cm emission in which the beam subtends radii of > 10 kpc. We therefore apply the column density profile of the Milky Way, in addition to the mean of the sample, observed at sufficiently high resolution, and the mean profile for the near-by galaxies in the IllustrisTNG simulations. All of the models yield a peak in the mean spin temperature at similar radii/impact parameters (10 - 15 kpc) as the measured column densities. These radii are similar to those of the spiral arms where HII regions are often concentrated. We therefore suggest that the elevated spin temperatures trace the HII regions observed in the outer disk of many spiral galaxies.
