Polarimetry of hydrogen-poor superluminous supernovae
Polarimetry of hydrogen-poor superluminous supernovae
复制标题
贫氢超发光超新星的偏振测量
DOI：
10.1051/0004-6361/202345945
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发表时间：
2023
影响因子：
6.5
通讯作者：
Maund, J.
中科院分区：
文献类型：
--
作者：
Pursiainen, M.;Leloudas, G.;Cikota, A.;Bulla, M.;Inserra, C.;Patat, F.;Wheeler, J. C.;Aamer, A.;Gal-Yam, A.;Maund, J.
我们提出了七个贫氢超亮超新星（SLSNe-I），其中只有一个以前发表的偏振数据的线性偏振。研究得最好的事件是SN 2017 gci，我们在休息帧中的峰后+3 d和+29 d提供了两个分光偏振测量时期，伴随着四个成像偏振测量时期，直到+108 d。 在+3天的分光偏振测量显示出向红波长方向偏振度P增加，并显示出轴对称的迹象，但在+29天，P在整个光谱中为0，这意味着SN 2017 gci的光球层在峰值后的第一个月从轻微的非球面结构演变为更接近球形的结构。 然而，在50 + 55 d时P增加到0.5%，伴随着与+3 d相比不同的轴对称取向，意味着在该阶段存在额外的偏振源。 偏振的增加可能是由与星周物质（CSM）的相互作用引起的，正如光变曲线中的拐点和可能在同一相位检测到宽Hα发射所表明的那样。我们还分析了所有16个SLSNe-I的样品与偏振测量的日期。早期光谱阶段的数据显示出一致的低偏振，表明至少接近球形光球。没有明确的偏振和光谱相位之间的关系，被认为是当光谱类似于Ic型SNe在光球和星云阶段。光变曲线下降率，跨越一个因素的8，也没有显示出明确的关系与偏振特性。虽然只有缓慢演变的SLSNe-I显示出非零极化，但快速演变的SLSNe-I在足够晚的时间内没有被观察到，因此无法得出结论，它们都没有表现出变化的P。然而，随着偏振度的增加，四个SLSNe-I也有不规则的光变曲线下降。对于多达一半的人，光度，光谱和偏振特性的影响CSM相互作用。因此，CSM相互作用显然在理解SLSNe-I的极化演化中起着重要作用。
We present linear polarimetry for seven hydrogen-poor superluminous supernovae (SLSNe-I) of which only one has previously published polarimetric data. The best-studied event is SN 2017gci, for which we present two epochs of spectropolarimetry at +3 d and +29 d post-peak in rest frame, accompanied by four epochs of imaging polarimetry up to +108 d. The spectropolarimetry at +3 d shows increasing polarisation degreePtowards the redder wavelengths and exhibits signs of axial symmetry, but at +29 d,P∼ 0 throughout the spectrum, implying that the photosphere of SN 2017gci evolved from a slightly aspherical configuration to a more spherical one in the first month post-peak. However, an increase ofPto ∼0.5% at ∼ + 55 d accompanied by a different orientation of the axial symmetry compared to +3 d implies the presence of additional sources of polarisation at this phase. The increase in polarisation is possibly caused by interaction with circumstellar matter (CSM), as already suggested by a knee in the light curve and a possible detection of broad Hαemission at the same phase. We also analysed the sample of all 16 SLSNe-I with polarimetric measurements to date. The data taken during the early spectroscopic phase show consistently low polarisation, indicating at least nearly spherical photospheres. No clear relation between the polarimetry and spectral phase was seen when the spectra resemble Type Ic SNe during the photospheric and nebular phases. The light-curve decline rate, which spans a factor of eight, also shows no clear relation with the polarisation properties. While only slow-evolving SLSNe-I have shown non-zero polarisation, the fast-evolving ones have not been observed at sufficiently late times to conclude that none of them exhibit changingP. However, the four SLSNe-I with increasing polarisation degree also have irregular light-curve declines. For up to half of them, the photometric, spectroscopic, and polarimetric properties are affected by CSM interaction. As such, CSM interaction clearly plays an important role in understanding the polarimetric evolution of SLSNe-I.