SN 2014ab: an aspherical Type IIn supernova with low polarization
SN 2014ab: an aspherical Type IIn supernova with low polarization
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DOI：
10.1093/mnras/staa2617
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发表时间：
2020-07
影响因子：
4.8
通讯作者：
C. Bilinski;N. Smith;G. Williams;Paul S. Smith;J. Andrews;K. Clubb;Wei Zheng;A. Filippenko;O. Fox;G. Hosseinzadeh;D. Howell;P. Kelly;P. Milne;D. Sand;J. Hoffman;D. Leonard;Samantha K. Cargill;Chadwick F. E. Casper;Goni Halevy;Haejung Kim;Sahana Kumar;Kenia Pina;H. Yuk
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文献类型：
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作者：
C. Bilinski;N. Smith;G. Williams;Paul S. Smith;J. Andrews;K. Clubb;Wei Zheng;A. Filippenko;O. Fox;G. Hosseinzadeh;D. Howell;P. Kelly;P. Milne;D. Sand;J. Hoffman;D. Leonard;Samantha K. Cargill;Chadwick F. E. Casper;Goni Halevy;Haejung Kim;Sahana Kumar;Kenia Pina;H. Yuk
我们目前的光度，光谱和分光光度法的超新星（SN）2014 ab，通过$\sim 200$天后达到峰值亮度。SN 2014 ab是一个明亮的IIn型SN（$M_V <-19.14 $mag），在其宿主星系VV 306 c的核心附近达到峰值亮度后被发现。发现前上限将爆炸时间限制在发现前200天内。虽然SN 2014 ab在我们的观测过程中下降了1等，但观测到的光谱保持显著不变。光谱表现出一个不对称的发射线轮廓与一贯较强的蓝移分量，这表明尘埃的存在或缺乏对称性之间的远侧和近侧的SN。Pa$\beta$的发射线显示的轮廓非常相似的H$\alpha$，这意味着这种更强的蓝移分量是通过大的尘埃颗粒，光学厚的材料掩星，或缺乏对称性之间的远侧和近侧的相互作用区域。尽管有这些不对称的线轮廓，我们的光谱偏振数据显示，SN 2014 ab在考虑星际偏振后几乎没有检测到偏振。这意味着我们看到的是一个光球层的辐射，它的正面与圆对称只有很小的偏差，我们很可能看到一个SN IIn，它在垂直于我们视线的平面上几乎是圆对称的，但是沿着我们的视线，它要么是大颗粒的尘埃，要么是星周物质或SN喷出物的密度明显不对称。我们认为SN 2014 ab和SN 2010 jl（以及其他SNe IIn）可能是从不同方向观察的类似事件。
We present photometry, spectra, and spectropolarimetry of supernova (SN) 2014ab, obtained through $\sim 200$ days after peak brightness. SN 2014ab was a luminous Type IIn SN ($M_V < -19.14$ mag) discovered after peak brightness near the nucleus of its host galaxy, VV 306c. Prediscovery upper limits constrain the time of explosion to within 200 days prior to discovery. While SN 2014ab declined by $\sim 1$ mag over the course of our observations, the observed spectrum remained remarkably unchanged. Spectra exhibit an asymmetric emission-line profile with a consistently stronger blueshifted component, suggesting the presence of dust or a lack of symmetry between the far side and near side of the SN. The Pa$\beta$ emission line shows a profile very similar to that of H$\alpha$, implying that this stronger blueshifted component is caused either through obscuration by large dust grains, occultation by optically thick material, or a lack of symmetry between the far side and near side of the interaction region. Despite these asymmetric line profiles, our spectropolarimetric data show that SN 2014ab has little detected polarization after accounting for the interstellar polarization. This suggests that we are seeing emission from a photosphere that has only small deviation from circular symmetry face-on. We are likely seeing a SN IIn with nearly circular symmetry in the plane normal to our line of sight, but with either large-grain dust or significant asymmetry in the density of circumstellar material or SN ejecta along our line of sight. We suggest that SN 2014ab and SN 2010jl (as well as other SNe IIn) may be similar events viewed from different directions.