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arXiv 2006.03057astro-ph.GAastro-ph.HEastro-ph.SR
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26Al在银盘中的分布和运动学

Distribution and kinematics of 26Al in the Galactic disc

Yusuke Fujimoto, Mark R. Krumholz, Shu-ichiro Inutsuka

摘要:

铝26是一种短寿命的放射性同位素,被认为是由大质量恒星风和超新星注入到星际介质中的。然而,26Al辐射的全天分布图显示了比大质量恒星或冷ISM更大的尺度高度和更快的旋转速度。我们调查这种差异的起源使用N体+流体动力学模拟银河系,自洽包括自引力,恒星形成,恒星反馈,和26铝生产。我们没有发现银河系螺旋结构解释26Al异常的证据。恒星和它们产生的26Al气泡沿着螺旋臂形成,但是,由于我们的模拟产生自发产生的物质臂,而不是由外部电势强迫的传播臂,恒星形成发生在臂中心而不是前缘。结果发现,26Al的标度高度和旋转速度与冷ISM相似。然而,我们还表明,一个合成的26铝发射地图产生的一个可能的太阳位置在一个大的26铝泡沫的边缘恢复了许多主要的定性特征观察到的26铝天空。这表明观察到的异常26 Al分布是附近最近超新星产生的26 Al前景发射的产物。

英文摘要:

26Al is a short-lived radioactive isotope thought to be injected into the interstellar medium (ISM) by massive stellar winds and supernovae. However, all-sky maps of 26Al emission show a distribution with a much larger scale height and faster rotation speed than either massive stars or the cold ISM. We investigate the origin of this discrepancy using an N-body+hydrodynamics simulation of a Milky-Way-like galaxy, self-consistently including self-gravity, star formation, stellar feedback, and 26Al production. We find no evidence that the Milky Way's spiral structure explains the 26Al anomaly. Stars and the 26Al bubbles they produce form along spiral arms, but, because our simulation produces material arms that arise spontaneously rather than propagating arms forced by an external potential, star formation occurs at arm centres rather than leading edges. As a result, we find a scale height and rotation speed for 26Al similar to that of the cold ISM. However, we also show that a synthetic 26Al emission map produced for a possible Solar position at the edge of a large 26Al bubble recovers many of the major qualitative features of the observed 26Al sky. This suggests that the observed anomalous 26Al distribution is the product of foreground emission from the 26Al produced by a nearby, recent supernova.

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