论文标题
Meerkat看到的NGC 4945的延长HI Halo
The extended HI halo of NGC 4945 as seen by MeerKAT
论文作者
论文摘要
介绍了用Meerkat的核星爆球体NGC 4945中中性原子氢（HI）的观察。我们发现大量的Halo气体，以前被HI观测值遗漏，占HI质量总数的6.8％。这很可能是通过恒星形成吹入光环中的气体。我们的地图降至$3σ$列密度的水平$ 5 \ times10^{18} cm^{ - 2} $。我们使用倾斜型拟合技术对HI分布进行建模，并在银河系的接近和后退侧面找到翘曲。银河系北侧的HI似乎被抑制了。如先前的研究所示，这可能是星系中星系中的星爆活动电离的结果。经线的起源尚不清楚，但可能是由于过去的相互作用或RAM压力剥离所致。宽，不对称的HI吸收系线延伸到HI发射速度通道以外的NGC 4945的核区域都存在。这种宽线表明存在以高圆速度移动的核环。这是由HI吸收速度场中的清晰旋转模式支持的。吸收光谱的不对称性可能是由NGC 4945核区域中的流出或气体流出引起的。连续图显示了银河系主要轴两侧的较小延伸，这可能是由于Starburst活性而导致的溢出迹象。
Observations of the neutral atomic hydrogen (HI) in the nuclear starburst galaxy NGC 4945 with MeerKAT are presented. We find a large amount of halo gas, previously missed by HI observations, accounting for 6.8% of the total HI mass. This is most likely gas blown into the halo by star formation. Our maps go down to a $3σ$ column density level of $5\times10^{18} cm^{-2}$ . We model the HI distribution using tilted-ring fitting techniques and find a warp on the galaxy's approaching and receding sides. The HI in the northern side of the galaxy appears to be suppressed. This may be the result of ionisation by the starburst activity in the galaxy, as suggested by a previous study. The origin of the warp is unclear but could be due to past interactions or ram pressure stripping. Broad, asymmetric HI absorption lines extending beyond the HI emission velocity channels are present towards the nuclear region of NGC 4945. Such broad lines suggest the existence of a nuclear ring moving at a high circular velocity. This is supported by the clear rotation patterns in the HI absorption velocity field. The asymmetry of the absorption spectra can be caused by outflows or inflows of gas in the nuclear region of NGC 4945. The continuum map shows small extensions on both sides of the galaxy's major axis that might be signs of outflows resulting from the starburst activity.
