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arXiv 1408.6239astro-ph.SRastro-ph.COastro-ph.HE
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Ia-CSM型超新星的性质:SN 2012 ca和SN 2013 dn的光学和近红外光谱

On the Nature of Type Ia-CSM Supernovae: Optical and Near-Infrared Spectra of SN 2012ca and SN 2013dn

Ori D. Fox, Jeffrey M. Silverman, Alexei V. Filippenko, Jon Mauerhan, Juliette Becker, H. Jacob Borish, S. Bradley Cenko, Kelsey I. Clubb, Melissa Graham, Eric … 展开作者

Ori D. Fox, Jeffrey M. Silverman, Alexei V. Filippenko, Jon Mauerhan, Juliette Becker, H. Jacob Borish, S. Bradley Cenko, Kelsey I. Clubb, Melissa Graham, Eric Hsiao, Patrick L. Kelly, William H. Lee, G. H. Marion, Dan Milisavljevic, Jerod Parrent, Isaac Shivvers, Michael Skrutskie, Nathan Smith, John Wilson, Weikang Zheng

摘要:

越来越多的Ia型超新星(SNe Ia)显示出与致密的星周介质(SNe Ia-CSM)发生意外相互作用的证据。然而,由于CSM相互作用的强大贡献所产生的光谱模糊性,祖细胞的确切性质仍然存在争议。后期的光谱提供了潜在的洞察力,如果后冲击冷,致密壳变得足够薄和/或喷出物开始穿越反向冲击。迄今为止,这种高质量的光谱很少存在。在这里,我们报告了SNe~Ia-CSM 2012 ca和2013 dn的后期光学和红外光谱。这些SNe Ia-CSM光谱显示出低[Fe III]/[Fe II]比值和强[Ca II]在晚时期。这些特征让人想起了超级大塞卡质量(SC)的候选者SN 2009 dc,这些特征暗示了由于高密度而导致的低电离状态,尽管广泛的Fe特征无可否认地显示出与在一些核心坍缩的SN e Ibn和IIn中观察到的蓝色“准连续体”的相似性。SN 2012 ca和其他SN e Ia-CSM都没有在光谱中显示出宽氧、碳或镁的证据。与SN 2005 ip中的I型相互作用类似,SN 2012 ca中也发现了许多高电离线,包括[S III]、[Ar III]、[Ar X]、[Fe VIII]、[Fe X],可能还有[Fe XI]。总的辐射热能量输出不超过10^51 erg,但确实需要很大的动力学-辐射转换效率。所有这些观测结果表明,SNe Ia-CSM更符合热核爆炸而不是核心坍塌事件,尽管详细的辐射转移模型肯定是必要的,以证实这些结果。

英文摘要:

A growing subset of Type Ia supernovae (SNe Ia) show evidence for unexpected interaction with a dense circumstellar medium (SNe Ia-CSM). The precise nature of the progenitor, however, remains debated owing to spectral ambiguities arising from a strong contribution from the CSM interaction. Late-time spectra offer potential insight if the post-shock cold, dense shell becomes sufficiently thin and/or the ejecta begin to cross the reverse shock. To date, few high-quality spectra of this kind exist. Here we report on the late-time optical and infrared spectra of the SNe~Ia-CSM 2012ca and 2013dn. These SNe Ia-CSM spectra exhibit low [Fe III]/[Fe II] ratios and strong [Ca II] at late epochs. Such characteristics are reminiscent of the super-Chandrasekhar-mass (SC) candidate SN 2009dc, for which these features suggested a low-ionisation state due to high densities, although the broad Fe features admittedly show similarities to the blue "quasi-continuum" observed in some core-collapse SNe Ibn and IIn. Neither SN 2012ca nor any of the other SNe Ia-CSM show evidence for broad oxygen, carbon, or magnesium in their spectra. Similar to the interacting Type IIn SN 2005ip, a number of high-ionisation lines are identified in SN 2012ca, including [S III], [Ar III], [Ar X], [Fe VIII], [Fe X], and possibly [Fe XI]. The total bolometric energy output does not exceed 10^51 erg, but does require a large kinetic-to-radiative conversion efficiency. All of these observations taken together suggest that SNe Ia-CSM are more consistent with a thermonuclear explosion than a core-collapse event, although detailed radiative transfer models are certainly necessary to confirm these results.

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