12CO(3-2) Emission in Spiral Galaxies: Warm Molecular Gas in Action?
12CO(3-2) Emission in Spiral Galaxies: Warm Molecular Gas in Action?
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螺旋星系中的 12CO(3-2) 排放：热分子气体在起作用？
DOI：
10.1086/587872
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
M. Rubio
中科院分区：
文献类型：
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作者：
G. Galaz;P. Cortés;L. Bronfman;M. Rubio
利用APEX亚毫米波望远镜研究了5个正面邻近棒旋星系的~（12）CO（3-2）辐射，其中3个是位于Freeman极限的高表面亮度星系（HSBs），2个是低表面亮度星系（LSBs）。我们对三个HSB螺旋中的两个有阳性检测，对LSB没有检测。对于具有阳性检测的星系（NGC 0521和PGC 070519），辐射仅限于它们的凸起，速度色散分别为~90和~73 km s-1，积分强度分别为1.20和0.76 K km s-1。对于未检测到的，估计的上限为综合强度为~0.54 K km s-1。根据这些数据，我们可以估算出H2的质量以及原子与分子的质量比。虽然所有的星系都是棒星系，我们观察到的12 CO（3-2）发射只有突出的酒吧星系。我们推测，酒吧可以动态地有利于12 CO（3-2）的排放，作为第二个参数后，表面亮度。因此，长期演化可能在推动分子气体（如12 CO（3-2））的碰撞跃迁中发挥重要作用，特别是在LSB中。
Using the APEX submillimeter telescope we have investigated the 12CO(3-2) emission in five face-on nearby barred spiral galaxies, where three of them are high surface brightness galaxies (HSBs) lying at the Freeman limit, and two are low surface brightness galaxies (LSBs). We have positive detections for two of three HSB spirals and nondetections for the LSBs. For the galaxies with positive detection (NGC 0521 and PGC 070519), the emission is confined to their bulges, with velocity dispersions of ~90 and ~73 km s-1 and integrated intensities of 1.20 and 0.76 K km s-1, respectively. For the nondetections, the estimated upper limit for the integrated intensity is ~0.54 K km s-1. With these figures we estimate the H2 masses as well as the atomic-to-molecular mass ratios. Although all the galaxies are barred, we observe 12CO(3-2) emission only for galaxies with prominent bars. We speculate that bars could dynamically favor the 12CO(3-2) emission, as a second parameter after surface brightness. Therefore, secular evolution could play a major role in boosting collisional transitions of molecular gas, such as 12CO(3-2), especially in LSBs.