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arXiv 0903.0217astro-ph.GAastro-ph.SR
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超新星中的尘埃:形成和演化

Dust in Supernovae; Formation and Evolution

Takashi Kozasa, Takaya Nozawa, Nozomu Tominaga, Hideyuki Umeda, Keiichi Maeda, Ken'ichi Nomoto

摘要:

核心坍缩超新星(CCSNe)一直被认为是宇宙尘埃的来源之一。在喷出物中形成的尘埃的种类和质量的多少,并注入到星际介质(ISM)取决于CCSNe的类型,通过外壳的厚度(质量)的差异。本文在总结了CCSNe尘埃形成观测的现有结果后,对II-P型和IIb型SNe超新星遗迹中尘埃的形成及其演化进行了研究。在此基础上,给出了IIb型SN信噪比下尘埃热辐射的时间演化,并与Cas A观测结果进行了比较。我们发现,在喷出物中形成的总尘埃质量并不依赖于类型; $\sim 0.3-0.7 M_{\odot}$在类型II-P SN和$\sim 0.13 M_{\odot}$在类型IIb SN。然而,尘埃的大小敏感地取决于类型,受到喷出物中气体密度差异的影响:尘埃质量主要是由半径大于0.03 $μ$ m的颗粒在II-P型,小于0.006 $μ$ m的IIb型,这决定了SNR中尘埃的命运。对于$n_{\rm H}=10.0-1.0$ cm $^{-3}$的环境氢密度,在II-P SNe型SNR中,幸存的尘埃质量为$\sim 0.04-0.2 M_{\odot}$,而在IIb型SNR中几乎所有的尘埃颗粒都被破坏。信噪比下尘埃热辐射的谱能量分布较好地反映了信噪比下尘埃粒子在溅射和随机加热作用下的演化过程。IIb型SN的尘埃形成和演化模型合理地再现了Cas A SNR的实测SED。

英文摘要:

Core--collapsed supernovae (CCSNe) have been considered to be one of sources of dust in the universe. What kind and how much mass of dust are formed in the ejecta and are injected into the interstellar medium (ISM) depend on the type of CCSNe, through the difference in the thickness (mass) of outer envelope. In this review, after summarizing the existing results of observations on dust formation in CCSNe, we investigate formation of dust in the ejecta and its evolution in the supernova remnants (SNRs) of Type II--P and Type IIb SNe. Then, the time evolution of thermal emission from dust in the SNR of Type IIb SN is demonstrated and compared with the observation of Cas A. We find that the total dust mass formed in the ejecta does not so much depend on the type; $\sim 0.3-0.7 M_{\odot}$ in Type II--P SNe and $\sim 0.13 M_{\odot}$ in Type IIb SN. However the size of dust sensitively depends on the type, being affected by the difference in the gas density in the ejecta: the dust mass is dominated by grains with radii larger than 0.03 $μ$m in Type II-P, and less than 0.006 $μ$m in Type IIb, which decides the fate of dust in the SNR. The surviving dust mass is $\sim 0.04-0.2 M_{\odot}$ in the SNRs of Type II--P SNe for the ambient hydrogen density of $n_{\rm H}=10.0-1.0$ cm$^{-3}$, while almost all dust grains are destroyed in the SNR of Type IIb. The spectral energy distribution (SED) of thermal emission from dust in SNR well reflects the evolution of dust grains in SNR through erosion by sputtering and stochastic heating. The observed SED of Cas A SNR is reasonably reproduced by the model of dust formation and evolution for Type IIb SN.

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