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arXiv 1003.0778astro-ph.GA
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用超新星研究小尺度ISM结构

Studying the small scale ISM structure with supernovae

F. Patat, N. L. J. Cox, J. Parrent, D. Branch

摘要:

目标。在这项工作中,我们探讨了使用快速膨胀的Ia型超新星光球检测银河系外ISM柱密度变化的空间尺度上的~100 AU的时间尺度上的几个月的可能性。方法.我们建立了一个简单的模型,它描述了扩大的photodisk和补丁星际云的影响,所观察到的Na I D线的等效宽度。利用这个模型,我们推导出的行为的等效宽度作为时间,空间尺度和柱密度波动幅度的函数。结果计算表明,Na I柱密度超过10^11 cm^-2的孤立的小云团(小于100 AU)很容易被探测到。相比之下,在一小部分情况下,更真实的、斑片状的ISM的影响是可以测量的,并且在1000天文单位的尺度上,峰-峰变化大于~10^12 cm^-2。结论.该技术提供了一种独特的方法来探测河外小尺度结构,这是迄今为止使用的任何方法都无法达到的。同样的工具也可以应用于研究亚AU银河ISM结构。

英文摘要:

AIMS. In this work we explore the possibility of using the fast expansion of a Type Ia supernova photosphere to detect extra-galactic ISM column density variations on spatial scales of ~100 AU on time scales of a few months. METHODS. We constructed a simple model which describes the expansion of the photodisk and the effects of a patchy interstellar cloud on the observed equivalent width of Na I D lines. Using this model we derived the behavior of the equivalent width as a function of time, spatial scale and amplitude of the column density fluctuations. RESULTS. The calculations show that isolated, small (<100 AU) clouds with Na I column densities exceeding a few 10^11 cm^-2 would be easily detected. In contrast, the effects of a more realistic, patchy ISM become measurable in a fraction of cases, and for peak-to-peak variations larger than ~10^12 cm^-2 on a scale of 1000 AU. CONCLUSIONS. The proposed technique provides a unique way to probe the extra-galactic small scale structure, which is out of reach for any of the methods used so far. The same tool can also be applied to study the sub-AU Galactic ISM structure.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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