Extinction curves flattened by reverse shocks in supernovae
Extinction curves flattened by reverse shocks in supernovae
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DOI：
10.1111/j.1365-2966.2007.12834.x
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发表时间：
2008-01
影响因子：
4.8
通讯作者：
H. Hirashita;T. Nozawa;Tsutomu T. Takeuchi Takashi Kozasa Univ. Tsukuba;Hokkaido Univ.;N. Univ.
中科院分区：
文献类型：
--
作者：
H. Hirashita;T. Nozawa;Tsutomu T. Takeuchi Takashi Kozasa Univ. Tsukuba;Hokkaido Univ.;N. Univ.
我们研究了年轻星系的消光曲线，其中的尘埃由 II 型超新星 (SNe II) 和/或不稳定对超新星 (PISNe) 提供。由于在高红移（z > 5）下，低质量恒星不能成为尘埃颗粒的主要来源，超新星 II 和 PISNe 的前身是寿命短的大质量恒星，应该控制尘埃的产生。在这里，我们从理论上研究了 SNe II 和 PISNe 产生的尘埃的消光曲线，考虑到与周围星际介质碰撞引起的反向冲击破坏。我们发现消光曲线对 SN 周围的环境气体密度敏感，因为反向冲击破坏的效率强烈依赖于它。这种破坏对于小尺寸颗粒特别有效，导致光学和紫外波长的消光曲线平坦。像nH 1c m -3 这样大的环境密度产生的消光曲线过于平坦，与在z = 6.2处观察到的SDSS J1048+4637的消光曲线不一致。尽管消光曲线对环境密度高度敏感，但当前观测限制仍然允许尘埃主要由 z ∼ 6 处的超新星形成的假设。为了进一步量化，应通过其他一些方法获得环境密度。最后，我们还讨论了我们的结果对于高 z 星系观测的重要性，强调了平坦消光曲线的可能性。
We investigate the extinction curves of young galaxies in which dust is supplied from Type II supernovae (SNe II) and/or pair instability supernovae (PISNe). Since at high redshift (z > 5), low-mass stars cannot be dominant sources for dust grains, SNe II and PISNe, whose progenitors are massive stars with short lifetimes, should govern the dust production. Here, we theoretically investigate the extinction curves of dust produced by SNe II and PISNe, taking into account reverse shock destruction induced by collision with ambient interstellar medium. We find that the extinction curve is sensitive to the ambient gas density around a SN, since the efficiency of reverse shock destruction strongly depends on it. The destruction is particularly efficient for small-sized grains, leading to a flat extinction curve in the optical and ultraviolet wavelengths. Such a large ambient density as nH 1c m −3 produces too flat an extinction curve to be consistent with the observed extinction curve for SDSS J1048+4637 at z = 6.2. Although the extinction curve is highly sensitive to the ambient density, the hypothesis that the dust is predominantly formed by SNe at z ∼ 6 is still allowed by the current observational constraints. For further quantification, the ambient density should be obtained by some other methods. Finally, we also discuss the importance of our results for observations of high-z galaxies, stressing a possibility of flat extinction curves.