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arXiv 1606.00872astro-ph.SRastro-ph.HE
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Ia/IIn型超新星PS15si的光学和近红外研究

An Optical and Near-Infrared Study of the Type Ia/IIn Supernova PS15si

Charles D. Kilpatrick, Jennifer E. Andrews, Nathan Smith, Peter Milne, George H. Rieke, WeiKang Zheng, Alexei V. Filippenko

摘要:

我们提出了超新星(SN)PS15 si的光学/近红外光谱和光度学。这个物体最初被确定为IIn型SN,但在这里,我们认为它应该被重新分类为Ia型SN,其窄氢线源于与星周物质的相互作用(CSM;即,SN Ia/IIn或SN Ia-CSM)。基于深未检测发现前27天,我们推断,这个SN被发现的光学极大值附近或稍早,我们估计的大致时间,它达到R-波段最大值的基础上与其他SNe Ia/IIn比较。在光谱形态方面,我们发现PS15 Si可以匹配到一系列的超新星Ia光谱类型,虽然SN 1991 T-类超新星Ia提供了最自洽的匹配。虽然这一观测结果与大多数其他超新星Ia/IIn的分析一致,但我们发现,当CSM的亮度要比下面的SN高出几个量级时,隐含的CSM亮度太低,无法解释SN的整体亮度。我们推断,PS15 Si和SN 1991 T的热,过亮,高电离光谱之间的相似性是一个光谱的结果,起源于喷出物层,由CSM相互作用的紫外线/X射线辐射加热。此外,PS15 si可能在发现后85天左右在B和V波段的短时间内重新变亮,这可能表明SN喷出物与大半径的团块或壳产生的CSM局部增强相互作用。

英文摘要:

We present optical/near-infrared spectroscopy and photometry of the supernova (SN) PS15si. This object was originally identified as a Type IIn SN, but here we argue that it should be reclassified as a Type Ia SN with narrow hydrogen lines originating from interaction with circumstellar matter (CSM; i.e., SN Ia/IIn or SN Ia-CSM). Based on deep nondetections 27 days before discovery, we infer that this SN was discovered around or slightly before optical maximum, and we estimate the approximate time that it reached R-band maximum based on comparison with other SNe Ia/IIn. In terms of spectral morphology, we find that PS15si can be matched to a range of SN Ia spectral types, although SN 1991T-like SNe Ia provides the most self-consistent match. While this observation agrees with analysis of most other SNe Ia/IIn, we find that the implied CSM luminosity is too low to account for the overall luminosity of the SN at a time when the CSM should outshine the underlying SN by a few magnitudes. We infer that the similarity between PS15si and the hot, overluminous, high-ionisation spectrum of SN 1991T is a consequence of a spectrum that originates in ejecta layers that are heated by ultraviolet/X-ray radiation from CSM interaction. In addition, PS15si may have rebrightened over a short timescale in the B and V bands around 85 days after discovery, perhaps indicating that the SN ejecta are interacting with a local enhancement in CSM produced by clumps or a shell at large radii.

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