SUBARU AND KECK OBSERVATIONS OF THE PECULIAR TYPE IA SUPERNOVA 2006GZ AT LATE PHASES
SUBARU AND KECK OBSERVATIONS OF THE PECULIAR TYPE IA SUPERNOVA 2006GZ AT LATE PHASES
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DOI：
10.1088/0004-637x/690/2/1745
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发表时间：
2008-08
期刊：
影响因子：
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通讯作者：
K. Maeda;K. Kawabata;Weidong Li;Masaomi Tanaka;P. Mazzali;Takashi Hattori;K. Nomoto;A. Filippenko
中科院分区：
文献类型：
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作者：
K. Maeda;K. Kawabata;Weidong Li;Masaomi Tanaka;P. Mazzali;Takashi Hattori;K. Nomoto;A. Filippenko
最近，发现了一些特殊的Ia型超新星（SNe Ia），它们显示出异常大的峰值亮度。它们的亮度需要在爆炸期间喷射出超过1 M☉（56Ni），这表明它们可能起源于超级钱德拉塞卡质量白矮星。然而，这些物体的性质还没有被很好地理解。特别是，没有在爆炸后大约一年的后期阶段采集数据。我们报告了斯巴鲁和凯克对超新星Ia 2006gz的光谱和光度观测，它被归类为这些“超亮”超新星Ia之一。SN 2006gz的晚时行为与正常Ia型超新星明显不同，这加强了SN 2006gz与正常Ia型超新星属于不同亚类的观点。然而，后期发现的特殊特征并不容易与大量的56 - ni联系起来；SN是微弱的，缺乏[Fe ii]和[Fe iii]的辐射。如果大部分放射性能量以可见光的形式从SN喷射出来，就像正常的Ia型超新星一样，56Ni的质量不会超过0.3 M☉。我们讨论了解决这个问题的几种可能性。然而，根据有限的观察，我们无法最终确定哪个过程负责。一种有趣的可能性是，大部分发射可能会转移到更长的波长，这与其他Ia型超新星的情况不同，这可能与早期数据所显示的密集的富含c的区域有关。另一种可能的情况是，SN 2006gz虽然特别，但实际上在早期并没有明显过亮。
Recently, a few peculiar Type Ia supernovae (SNe Ia) that show exceptionally large peak luminosity have been discovered. Their luminosity requires more than 1 M☉ of 56Ni to be ejected during the explosion, suggesting that they might have originated from super-Chandrasekhar mass white dwarfs. However, the nature of these objects is not yet well understood. In particular, no data have been taken at late phases, about one year after the explosion. We report on Subaru and Keck optical spectroscopic and photometric observations of the SN Ia 2006gz, which had been classified as being one of these “overluminous” SNe Ia. The late-time behavior is distinctly different from that of normal SNe Ia, reinforcing the argument that SN 2006gz belongs to a different subclass than normal SNe Ia. However, the peculiar features found at late times are not readily connected to a large amount of 56Ni; the SN is faint, and it lacks [Fe ii] and [Fe iii] emissions. If the bulk of the radioactive energy escapes the SN ejecta as visual light, as is the case in normal SNe Ia, the mass of 56Ni does not exceed ∼0.3 M☉. We discuss several possibilities to remedy the problem. With the limited observations, however, we are unable to conclusively identify which process is responsible. An interesting possibility is that the bulk of the emission might be shifted to longer wavelengths, unlike the case in other SNe Ia, which might be related to dense C-rich regions as indicated by the early-phase data. Alternatively, it might be the case that SN 2006gz, though peculiar, was actually not substantially overluminous at early times.