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arXiv 0902.1440astro-ph.SR
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晚相极亮超新星2006 gy的光辐射探测

The Extremely Luminous Supernova 2006gy at Late Phase: Detection of Optical Emission from Supernova

Koji S. Kawabata, Masaomi Tanaka, Keiichi Maeda, Takashi Hattori, Ken'ichi Nomoto, Nozomu Tominaga, Masayuki Yamanaka

摘要:

我们在爆炸后400天对SN 2006 gy进行了光谱学和测光,斯巴鲁/FOCAS处于良好的视宁度状态。我们发现SN在爆炸后约200至约400天内褪色约3等(即,从峰值到约400天的约5 mag)。整体的光变曲线与56 Ni加热模型略有一致,尽管200天左右的平坦化表明光通量在~200天和~400天之间下降得更快。晚时谱在所有类型的超新星中是相当独特的。它显示出许多中等宽度(~2000 km/s FWHM)的发射线,例如,[Fe[2],[3],[4],[5]。与Ca II IR三重态相比,[O I] 6300,6364宽线的缺失和[Fe II]和[Ca II]线的弱将通过线发射区域中的适度高的电子密度来解释。这种高密度的假设似乎与SN 2006 gy的大量喷出物和低膨胀速度相一致。H-α线的光度小至约1x10^39 erg/s,与相似时期的正常II型超新星相当。我们的观察表明,强CSM相互作用几乎完成了约400天。如果晚期光通量完全由放射性衰变提供动力,则超新星爆发至少产生MNi ~ 3 Msun。在后期光谱中,在7400- 8800 AA处出现了几条异常的发射线,其中一些可能是由于爆炸时合成的Ti或Ni所致。(节略)

英文摘要:

We performed optical spectroscopy and photometry of SN 2006gy at late time, ~400 days after the explosion, with the Subaru/FOCAS in a good seeing condition. We found that the SN faded by ~3 mag from ~200 to ~400 days after the explosion (i.e., by ~5 mag from peak to ~400 days) in R band. The overall light curve is marginally consistent with the 56Ni heating model, although the flattening around 200 days suggests the optical flux declined more steeply between ~200 and ~400 days. The late time spectrum was quite peculiar among all types of SNe. It showed many intermediate width (~2000 km/s FWHM) emission lines, e.g., [Fe II], [Ca II], and Ca II. The absence of the broad [O I] 6300, 6364 line and weakness of [Fe II] and [Ca II] lines compared with Ca II IR triplet would be explained by a moderately high electron density in the line emitting region. This high density assumption seems to be consistent with the large amount of ejecta and low expansion velocity of SN 2006gy. The H-alpha line luminosity was as small as ~1x10^39 erg/s, being comparable with those of normal Type II SNe at similar epochs. Our observation indicates that the strong CSM interaction had almost finished by ~400 days. If the late time optical flux is purely powered by radioactive decay, at least M_Ni ~ 3 M_sun should be produced at the SN explosion. In the late phase spectrum, there were several unusual emission lines at 7400--8800 AA and some of them might be due to Ti or Ni synthesized at the explosion. (abridged)

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