论文标题
IA型Supernovae SN 2013AA和SN 2017CBV的近红外和光学模子光谱在NGC 5643中
Near-infrared and Optical Nebular-phase Spectra of Type Ia Supernovae SN 2013aa and SN 2017cbv in NGC 5643
论文作者
论文摘要
We present multi-wavelength time-series spectroscopy of SN 2013aa and SN 2017cbv, two Type Ia supernovae (SNe Ia) on the outskirts of the same host galaxy, NGC 5643. This work utilizes new nebular-phase near-infrared (NIR) spectra obtained by the Carnegie Supernova Project-II, in addition to previously published optical and NIR spectra.通过测量光学和NIR中的Nenbular相[Fe II]线，我们检查了爆炸运动学并测试文献中常用的几种发射线拟合技术的功效。 NIR [Fe II] 1.644 $μ$ M线可提供最强的速度测量，这是由于选择拟合方法和线条混合而导致的变化。还研究了由于选择不同的合适方法，初始拟合参数，连续性和线轮廓函数以及拟合区域边界而产生的对速度测量的影响。 NIR [Fe II]速度产生的径向移动方向与使用光学[Fe II] 7155 A线测得的速度相同，但是移位的尺寸始终如一，大大较低，指出了光学研究中的潜在问题。 NIR [Fe II] 1.644 $ $ M的发射曲线显示，SNE IA都缺乏明显的不对称性，并且观察到的低速度提高了校正宿主星系旋转的任何径向速度贡献的重要性。 NIR在NEBULAR相中测得的低[Fe II]速度在SN 2013AA和SN 2017CBV的紧密双层系统中脱节大多数祖细胞方案。 NIR [Fe II] 1.644 $μm线的时间演变也表明祖细胞中等高祖细胞中央密度和潜在的高磁场。在早期和晚期都很好地观察了这些同胞Sne IA，这为研究SNE IA的内在多样性提供了绝佳的机会。
We present multi-wavelength time-series spectroscopy of SN 2013aa and SN 2017cbv, two Type Ia supernovae (SNe Ia) on the outskirts of the same host galaxy, NGC 5643. This work utilizes new nebular-phase near-infrared (NIR) spectra obtained by the Carnegie Supernova Project-II, in addition to previously published optical and NIR spectra. By measuring nebular-phase [Fe II] lines in both the optical and NIR, we examine the explosion kinematics and test the efficacy of several emission line fitting techniques commonly used in the literature. The NIR [Fe II] 1.644 $μ$m line provides the most robust velocity measurements against variations due to the choice of the fit method and line blending. The resulting effects on velocity measurements due to choosing different fit methods, initial fit parameters, continuum and line profile functions, and fit region boundaries were also investigated. The NIR [Fe II] velocities yield the same radial shift direction as velocities measured using the optical [Fe II] 7155 A line, but the sizes of the shifts are consistently and substantially lower, pointing to a potential issue in optical studies. The NIR [Fe II] 1.644 $μ$m emission profile shows a lack of significant asymmetry in both SNe Ia, and the observed low velocities elevate the importance for correcting for any radial velocity contribution from the host galaxy's rotation. The low [Fe II] velocities measured in the NIR at nebular phases disfavors most progenitor scenarios in close double-degenerate systems for both SN 2013aa and SN 2017cbv. The time evolution of the NIR [Fe II] 1.644 $μ$m line also indicates moderately high progenitor white dwarf central density and potentially high magnetic fields. These sibling SNe Ia were well observed at both early and late times, providing an excellent opportunity to study the intrinsic diversity of SNe Ia.
