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arXiv 1005.2290astro-ph.CO
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用Herschel-PACS追踪暗星系中恒星形成的位置

Tracing the sites of obscured star formation in the Antennae galaxies with Herschel-PACS

Ulrich Klaas, Markus Nielbock, Martin Haas, Oliver Krause, Jürgen Schreiber

摘要:

相互作用星系的远红外成像甚至可以定位隐藏的恒星形成地点,并测量核内和核外恒星形成的相对强度。我们想在附近的银河系中找到恒星形成的地点。得益于欧空局赫歇尔空间天文台机载PACS相机前所未有的清晰度和深度,首次有可能通过70,100和160微米的扫描地图对FIR中的单个恒星形成结进行完整评估。我们使用团块提取光度学和SED诊断来推导与恒星形成活动相关的性质。PACS 70、100和160微米的图像沿着重叠区域中两个核之间的弧追踪了最近恒星形成的复杂结构。星爆节点的分辨率和额外的多波长数据允许分析它们各自的恒星形成历史和状态。特别是,在南核以东的中红外线(K1)中最明亮的结,在尘埃加热和恒星形成率,效率和密度方面表现出最高的活动。这个区域的直径只有2千秒差距,光度为10-1000微米,与我们的银河系一样高。它在射电-远红外线光度比中显示出最大的射电辐射不足,并且缺乏X射线辐射,因此将其归类为一个非常年轻的复合体。最亮的100和160微米发射区(K2),靠近碰撞前沿,由3个节点组成,也显示出高的恒星形成密度和效率,在其最模糊的部分缺乏X射线发射,但无线电与远红外线的光度比过大。这也暗示了一个年轻的阶段,但其星际介质的条件不同。我们的研究结果提供了重要的检查点的相互作用星系的数值模拟时,模拟恒星形成和恒星反馈。

英文摘要:

FIR imaging of interacting galaxies allows locating even hidden sites of star formation and measuring of the relative strength of nuclear and extra-nuclear star formation. We want to resolve the star-forming sites in the nearby system of the Antennae. Thanks to the unprecedented sharpness and depth of the PACS camera onboard ESA's Herschel Space Observatory, it is possible for the first time to achieve a complete assessment of individual star-forming knots in the FIR with scan maps at 70, 100, and 160 um. We used clump extraction photometry and SED diagnostics to derive the properties related to star-forming activity. The PACS 70, 100, and 160 um maps trace the knotty structure of the most recent star formation along an arc between the two nuclei in the overlap area. The resolution of the starburst knots and additional multi-wavelength data allow their individual star formation history and state to be analysed. In particular, the brightest knot in the mid-infrared (K1), east of the southern nucleus, exhibits the highest activity by far in terms of dust heating and star formation rate, efficiency, and density. With only 2 kpc in diameter, this area has a 10-1000 um luminosity, which is as high as that of our Milky Way. It shows the highest deficiency in radio emission in the radio-to-FIR luminosity ratio and a lack of X-ray emission, classifying it as a very young complex. The brightest 100 and 160 um emission region (K2), which is close to the collision front and consists of 3 knots, also shows a high star formation density and efficiency and lack of X-ray emission in its most obscured part, but an excess in the radio-to-FIR luminosity ratio. This suggests a young stage, too, but different conditions in its interstellar medium. Our results provide important checkpoints for numerical simulations of interacting galaxies when modelling the star formation and stellar feedback.

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