Circumstellar Light Echo as a Possible Origin of the Polarization of Type IIP Supernovae
Circumstellar Light Echo as a Possible Origin of the Polarization of Type IIP Supernovae
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DOI：
10.3847/1538-4357/aa8b0d
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发表时间：
2017-09
期刊：
影响因子：
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通讯作者：
T. Nagao;K. Maeda;Masaomi Tanaka
中科院分区：
文献类型：
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作者：
T. Nagao;K. Maeda;Masaomi Tanaka
IIP型超新星（SNe IIP）是最常见的核坍缩型超新星。它们往往在后期表现出偏振度的快速增加。这种时间演化通常被认为起源于内部非球面核的出现，而SN周围的星周尘埃（CS）的偏振散射回波的影响也可能对这种偏振特征有很大的贡献。在这项研究中，我们研究的散射回波对SN偏振的影响，通过辐射传输模拟各种几何形状和数量的CS尘埃。研究发现，不对称分布的CS尘埃，这是通常推断的红超巨星，可以重现所观察到的偏振功能。我们已经将我们的结果应用到SNe 2004dj和2006ov，推导CS尘埃的几何形状和数量来解释在这种情况下观察到的偏振特征。对于这两个SNe，斑点状或双极分布的CS灰尘，而不是盘状分布是有利的。SNe 2004dj和2006ov的团状模型（双极CS尘埃模型）中得出的尘埃质量分别为（）和（）。即使在这种情况下，该过程不会在所观察到的偏振信号中起主导作用，这种效应原则上也应该有助于它，其强度取决于CS尘埃的性质。因此，在通过偏振观测讨论超新星爆发的多维结构时，必须考虑这种效应。
Type IIP supernovae (SNe IIP) are the most common class of core-collapse SNe. They often show a rapid increase of polarization degree in the late phase. This time evolution is generally believed to originate from the emergence of an inner aspherical core, while the effect of polarized-scattered echoes by circumstellar (CS) dust around the SN may also substantially contribute to this polarization feature. In this study, we examine the effects of the scattered echoes on the SN polarization through radiative transfer simulations for various geometries and amounts of CS dust. It is found that asymmetrically distributed CS dust, which is generally inferred for red supergiants, can reproduce the observed polarization features. We have applied our results to SNe 2004dj and 2006ov, deriving the geometry and amount of CS dust to explain their observed polarization features in this scenario. For both SNe, the blob-like or bipolar distribution of CS dust rather than the disk-like distribution is favored. The derived dust masses in the blob model (the bipolar CS dust model) for SNe 2004dj and 2006ov are ( ) and ( ), respectively. Even in the case where this process would not play a dominant role in the observed polarization signals, this effect should in principle contribute to it, the strength of which depends on the nature of the CS dust. Therefore, this effect must be taken into account in discussing the multi-dimensional structure of an SN explosion through polarimetric observations.