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arXiv 0812.2828astro-ph
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星爆星系NGC 2146的分子超泡和外流

Molecular Superbubbles and Outflows from Starburst Galaxy NGC 2146

An-Li Tsai, Satoki Matsushita, Kouichiro Nakanishi, Kotaro Kohno, Ryohei Kawabe, Tatsuya Inui, Hironori Matsumoto, Takeshi G. Tsuru, Alison B. Peck, Andrea Tarchi

摘要:

本文介绍了利用野边山毫米波阵列(NMA)对附近边缘星暴星系NGC 2146中心60”区域进行的深度(每20.8 km s^{-1}速度通道1 sigma = 5.7 mJy光束)^{12}CO(1-0)干涉观测的结果。成功探测到两个扩散膨胀的分子超泡和一个分子外流。其中一个分子超泡位于银盘下方,大小约为1千秒差距,膨胀速度约为50 km s^{-1};另一个分子超泡大小约为700秒差距,膨胀速度约为35 km s^{-1},也出现在位置-速度图中;分子外流位于银盘上方,范围约为2千秒差距,以高达200公里/秒^{-1}的速度膨胀。分子外流具有弧形结构,位于软X射线外流的前沿。此外,分子外流的动能(~ 3E 55 erg)和压力(~1 E-12 \pm 1 dyne cm ^{-2})与热等离子体相当或更小,这表明热等离子体将分子气体从银盘中推出。在~1 kpc大小的分子超泡内部,似乎存在弥散的软X射线发射。但是由于超级气泡位于倾斜的星系盘后面,它大部分被分子气体吸收。

英文摘要:

We present results from a deep (1 sigma = 5.7 mJy beam^{-1} per 20.8 km s^{-1} velocity channel) ^{12}CO(1-0) interferometric observation of the central 60" region of the nearby edge-on starburst galaxy NGC 2146 observed with the Nobeyama Millimeter Array (NMA). Two diffuse expanding molecular superbubbles and one molecular outflow are successfully detected. One molecular superbubble, with a size of ~1 kpc and an expansion velocity of ~50 km s^{-1}, is located below the galactic disk; a second molecular superbubble, this time with a size of ~700 pc and an expansion velocity of ~35 km s^{-1}, is also seen in the position-velocity diagram; the molecular outflow is located above the galactic disk with an extent ~2 kpc, expanding with a velocity of up to ~200 km s^{-1}. The molecular outflow has an arc-like structure, and is located at the front edge of the soft X-ray outflow. In addition, the kinetic energy (~3E55 erg) and the pressure (~1 E-12 \pm 1 dyne cm ^{-2}) of the molecular outflow is comparable to or smaller than that of the hot thermal plasma, suggesting that the hot plasma pushes the molecular gas out from the galactic disk. Inside the ~1 kpc size molecular superbubble, diffuse soft X-ray emission seems to exist. But since the superbubble lies behind the inclined galactic disk, it is largely absorbed by the molecular gas.

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