Dust Destruction in the High-Velocity Shocks Driven by Supernovae in the Early Universe
Dust Destruction in the High-Velocity Shocks Driven by Supernovae in the Early Universe
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早期宇宙中超新星驱动的高速冲击中的尘埃破坏
DOI：
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发表时间：
2006
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影响因子：
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通讯作者：
A. Habe
中科院分区：
文献类型：
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作者：
T. Nozawa;T. Kozasa;A. Habe
研究了早期宇宙中超新星（SNe）驱动的高速星际激波中尘埃粒子的溅射破坏，揭示了尘埃破坏的时间尺度与星际介质（ISM）中气体密度nH，0以及SNe的前身质量Mpr和爆炸能量E51的关系.我们感兴趣的尘埃和离子物种的组合的溅射产率进行评估，通过应用所谓的通用关系与轻微的修改。尘埃颗粒的动力学和它们的破坏溅射在冲击计算考虑到每个尘埃物种的尺寸分布，连同在球对称冲击的气体的温度和密度的时间演化。计算结果表明，尘埃的破坏效率不仅取决于溅射产额，而且还取决于每个粒子的初始尺寸分布。粉尘破坏效率随E51和/或nH，0的增加而增加，但只要E51相同，则几乎与Mpr无关。被激波扫过的气体质量是E51的增函数和nH，0的减函数。结合这些结果，我们提出了在早期宇宙中的每个粒子物种的破坏的时间尺度的近似公式作为E51和nH，0的函数。该公式适用于研究金属丰度为Z <$10 -3 Z的宇宙早期尘埃粒子的演化。简要讨论了气体冷却过程对粉尘破坏的影响。
We investigate the destruction of dust grains by sputtering in the high-velocity interstellar shocks driven by supernovae (SNe) in the early universe to reveal the dependence of the timescale of dust destruction on the gas density nH,0 in the interstellar medium (ISM), as well as on the progenitor mass Mpr and explosion energy E51 of SNe. The sputtering yields for the combinations of dust and ion species of interest to us are evaluated by applying the so-called universal relation with a slight modification. The dynamics of dust grains and their destruction by sputtering in shocks are calculated by taking into account the size distribution of each dust species, together with the time evolution of the temperature and density of the gas in spherically symmetric shocks. The results of the calculations show that the efficiency of dust destruction depends not only on the sputtering yield but also on the initial size distribution of each grain species. The efficiency of dust destruction increases with increasing E51 and/or increasing nH,0 but is almost independent of Mpr as long as E51 is the same. The mass of gas swept up by a shock is an increasing function of E51 and a decreasing function of nH,0. Combining these results, we present the approximation formula for the timescale of destruction for each grain species in the early universe as a function of E51 and nH,0. This formula is applicable for investigating the evolution of dust grains at the early epoch of the universe with the metallicity of Z ≲ 10-3 Z☉. The effects of the cooling processes of gas on the destruction of dust are briefly discussed.