EXPLORING THE DUST CONTENT OF GALACTIC WINDS WITH HERSCHEL. I. NGC 4631
EXPLORING THE DUST CONTENT OF GALACTIC WINDS WITH HERSCHEL. I. NGC 4631
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与赫歇尔一起探索银河风的尘埃含量。
DOI：
10.1088/0004-637x/804/1/46
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
S. Teng
中科院分区：
文献类型：
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作者：
M. Meléndez;S. Veilleux;C. Martin;C. Engelbracht;J. Bland;G. Cecil;F. Heitsch;A. McCormick;T. Müller;D. Rupke;S. Teng
我们提出了一个详细的分析，深远红外观测附近的边缘上的恒星形成星系NGC 4631获得的赫歇尔空间天文台。我们的光电探测器阵列相机和光谱仪（PACS）在70和160 μm的图像显示了丰富的细丝和烟囱状特征，延伸到星系平面上方6 kpc的投影距离。PACS的特征通常与在该星系中观察到的面外Hα、射电连续谱和软X射线特征相匹配，表明该星系存在由星星形成调节的紧密盘晕连接。另一方面，在光谱和光度成像接收器250，350和500 μm数据中检测到的较大尺度上的较冷尘埃成分的形态与先前在NGC 4631中报告的平面外H I流相匹配，并表明潮汐起源。PACS 70/160 μm的比值在该星系核上方的中央10.3kpc区域（“超级气泡”）升高。逐像素分析表明，该区域的尘埃具有较高的温度和/或具有较陡光谱指数（β > 2？>）比磁盘中的灰尘更多，可能是超级气泡中更严酷的环境的结果。盘中的星星形成似乎不足以将物质从盘中提升出来，除非它在过去更活跃，或者超级气泡区域的尘埃与气体的比率高于银河系的值。光环中的一些尘埃也可能是从附近的同伴那里被潮汐剥离的，或者是通过星系间的相互作用从盘中被提起的。
We present a detailed analysis of deep far-infrared observations of the nearby edge-on star-forming galaxy NGC 4631 obtained with the Herschel Space Observatory. Our Photodetector Array Camera and Spectrometer (PACS) images at 70 and 160 μm show a rich complex of filaments and chimney-like features that extends up to a projected distance of 6 kpc above the plane of the galaxy. The PACS features often match extraplanar Hα, radio-continuum, and soft X-ray features observed in this galaxy, pointing to a tight disk–halo connection regulated by star formation. On the other hand, the morphology of the colder dust component detected on a larger scale in the Spectral and Photometric Imaging Receiver 250, 350, and 500 μm data matches the extraplanar H I streams previously reported in NGC 4631 and suggests a tidal origin. The PACS 70/160 μm ratios are elevated in the central ∼3.0 kpc region above the nucleus of this galaxy (the “superbubble”). A pixel-by-pixel analysis shows that dust in this region has a higher temperature and/or an emissivity with a steeper spectral index ( β > 2 ?> ) than the dust in the disk, possibly the result of the harsher environment in the superbubble. Star formation in the disk seems energetically insufficient to lift the material out of the disk, unless it was more active in the past or the dust-to-gas ratio in the superbubble region is higher than the Galactic value. Some of the dust in the halo may also have been tidally stripped from nearby companions or lifted from the disk by galaxy interactions.