论文标题
Cygnus a中的4 kpc分子气车道
A 4~Kpc Molecular Gas Lane in Cygnus A
论文作者
论文摘要
我们使用Alma CO 2-1观测表明，在Cygnus A宿主星系中发现了4 kPc分子气车道。气车道的定向大致垂直于投影的无线电射流轴。 CO发射通常遵循HST I波段图像中看到的块状灰尘车道。总分子气体质量为$ 30 \ times 10^8 $ m $ _ \ odot $用于银河系类型云，$ 3.6 \ times 10^8 $ m $ m $ _ \ odot $用于Starburst条件。从北部到南方峰的速度变化约为$ \ pm 175 $ 〜km〜s $^{ - 1} $，尽管中央地区的发射较弱，但峰之间的速度梯度显然平稳。在内部$ \ sim 0.5英寸0.5英寸$中，与无线电核心的预计距离相比，与h $ _2 $ _2 $ _2 $ 2.1218 $μ$ m发射的比较显示，振动兴奋的温暖分子气体的速度更高Radius $ \ SIM 1.5 $至$ 2英寸的块状戒指，而温暖的H $ _2 $ 2.12 $μ$ m $ $ m $ m $ m $ $ m $ $ m $ $ m $ $ $ $ m $ $ $ $ $ m $ $ $ $ $ $ m $ $ $ $ $ $ $ m $ m $ $ $ $ $ $ $ $ m $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ M M $ $ $ $ $ $ $ $ $ $ $ M M $ \ $ \ $ m m $ \ $ \ $ \ $ \ $ $ \ $ m m $。导致其他具有CO发射的射电星系的背景。
We present the discovery of a 4 kpc molecular gas lane in the Cygnus A host galaxy, using ALMA CO 2-1 observations. The gas lane is oriented roughly perpendicular to the projected radio jet axis. The CO emission generally follows the clumpy dust lanes seen in HST I-band images. The total molecular gas mass is $30\times 10^8$ M$_\odot$ for Milky Way type clouds, and $3.6 \times 10^8$ M$_\odot$ for starburst conditions. There is a velocity change from the northern to southern CO peaks of about $\pm 175$~km~s$^{-1}$, and an apparently smooth velocity gradient between the peaks, although the emission in the central region is weak. In the inner $\sim 0.5"$ projected distance from the radio core, comparison of the CO velocities to those observed for H$_2$ 2.1218 $μ$m emission shows higher velocities for the vibrationally excited warm molecular gas than the cooler CO 2-1 line emitting gas at similar projected radii. A possible explanation for these different projected velocities at a given radius is that the cooler CO gas is distributed in a clumpy ring at radius $\sim 1.5"$ to $2"$, while the warm H$_2$ 2.12$μ$m emitting gas is interior to this ring. Of course, the current data cannot rule-out a clumpy, amorphous molecular gas distribution linearly distributed perpendicular to the radio jet axis. We consider surface brightness properties on scales down to $\sim 265$~pc, and discuss the Cygnus A results in the context of other radio galaxies with CO emission.
