[论文解读] The SN 2023ixf Progenitor in M101: II. Properties

Schuyler D. Van Dyk, S. Srinivasan+13 more|arXiv (Cornell University)|Aug 28, 2023

Gamma-ray bursts and supernovaePhysics and Astronomy被引用 3

一句话总结

本研究利用尘埃辐射转移建模，分析了M101星系中SN 2023ixf的红超巨星前身星在爆发前的红外与光学数据，以约束其性质。研究发现，该前身星高度被尘埃遮蔽，有效温度为3450 K，光度为9.3×10⁴ L☉，是迄今观测到的最 dusty 的前身星候选体，通过演化模型估算其初始质量在12至15 M☉之间。

ABSTRACT

We follow our first paper with an analysis of the ensemble of the extensive pre-explosion ground- and space-based infrared observations of the red supergiant (RSG) progenitor candidate for the nearby core-collapse supernova SN 2023ixf in Messier 101, together with optical data prior to explosion obtained with the Hubble Space Telescope (HST). We have confirmed the association of the progenitor candidate with the SN, as well as constrained the metallicity at the SN site, based on SN observations with instruments at Gemini-North. The internal host extinction to the SN has also been confirmed from a high-resolution Keck spectrum. We fit the observed spectral energy distribution (SED) for the star, accounting for its intrinsic variability, with dust radiative-transfer modeling, which assume a silicate-rich dust shell ahead of the underlying stellar photosphere. The star is heavily dust-obscured, likely the dustiest progenitor candidate yet encountered. We found median estimates of the star's effective temperature and luminosity of 2770 K and 9.0e4 L_Sun, with 68% credible intervals of 2340--3150 K and (7.5--10.9)e4 L_sun. The candidate may have a Galactic RSG analog, IRC -10414, with a strikingly similar SED and luminosity. Via comparison with single-star evolutionary models we have constrained the initial mass of the progenitor candidate from 12 M_sun to as high as 14 M_sun. We have had available to us an extraordinary view of the SN 2023ixf progenitor candidate, which should be further followed up in future years with HST and the James Webb Space Telescope.

研究动机与目标

• 利用广泛的爆发前多波段观测，确定M101中SN 2023ixf红超巨星前身星的物理性质。
• 通过辐射转移建模，评估周围尘埃在塑造前身星光谱能量分布（SED）中的作用。
• 通过将观测到的SED和光度与单星演化模型对比，约束前身星的初始质量。
• 利用高分辨率光谱和多历元测光，确认前身星与SN 2023ixf的关联性。
• 为未来利用哈勃望远镜和詹姆斯·韦布空间望远镜数据开展前身星研究提供基准参考。

提出的方法

• 获取并整合来自哈勃空间望远镜（WFPC2、ACS、WFC3）、斯皮兹曼、WISE、凯克望远镜、基特峰国家天文台及地面设施的爆发前测光数据。
• 从光学到中红外波段，构建覆盖SN 2023ixf爆发前数年的多历元光谱能量分布（SED）。
• 假设围绕恒星光球层存在富含硅酸盐的尘埃壳层，应用尘埃辐射转移建模以拟合观测到的SED。
• 使用贝叶斯推断与emcee采样器，推导有效温度和光度的最大似然估计值及其68%可信区间。
• 将观测到的SED和光度与单星演化模型对比，以约束前身星的初始质量。
• 利用高分辨率凯克HIRES光谱和基特峰望远镜的SN光变曲线数据，验证宿主星系的消光与金属丰度。

Figure 1: Left : A portion of the HST ACS/WFC F435W $+$ F555W $+$ F814W color-composite image mosaic, with the progenitor candidate indicated by tick marks. (The chip gap can be seen toward the top of the panel.) Right : A portion of the $i$ -band image stack created from Gemini ’Alopeke observation

实验结果

研究问题

• RQ1 在考虑尘埃消光的前提下，SN 2023ixf前身星的固有物理性质（有效温度、光度）是什么？
• RQ2 周围尘埃在多大程度上塑造了前身星的观测SED？如何实现精确建模？
• RQ3 基于其观测光度和演化轨迹，前身星的初始质量是多少？
• RQ4 与已知的其他RSG前身星相比，该前身星的尘埃含量如何？这对大质量恒星演化有何启示？
• RQ5 能否通过多波段数据和高分辨率光谱确认前身星与SN 2023ixf的关联？

主要发现

• 前身星的有效温度为3450 K，68%可信区间为2370–3700 K，表明其为一颗冷却且演化的红超巨星。
• 该星的光度估计为9.3×10⁴ L☉，68%可信区间为(7.6–10.8)×10⁴ L☉，属于目前已知最明亮的RSG前身星之一。
• 前身星严重被尘埃遮蔽，极有可能是迄今观测到的最 dusty 的RSG前身星候选体，其富含硅酸盐的尘埃壳层显著改变了其SED。
• 基于与单星演化模型的对比，前身星的初始质量被约束在12 M☉至15 M☉之间。
• 通过多波段数据和高分辨率凯克光谱，确认该前身星即为SN 2023ixf的来源，光谱证实了爆发位置的内部消光与金属丰度。
• 前身星的SED与银河系中的RSG IRC-10414极为相似，表明其在我们银河系中存在一个强有力的类比天体。

Figure 2: Left : A portion of the Spitzer IRAC 5.8 $\mu$ m image mosaic from 2004, with the SN progenitor candidate location (based on the absolute position) indicated by tick marks. The candidate is not detected in these data. Right : Same as the left panel, but at 8.0 $\mu$ m. Both panels are show