The initial masses of the red supergiant progenitors to Type II supernovae
The initial masses of the red supergiant progenitors to Type II supernovae
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DOI：
10.1093/mnras/stx2734
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发表时间：
2017-09
影响因子：
4.8
通讯作者：
B. Davies;Emma R. Beasor
中科院分区：
文献类型：
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作者：
B. Davies;Emma R. Beasor
在档案爆炸前成像中检测到了越来越多的附近超新星的祖星。从这些图像中可以测量爆炸前几年的亮度，并最终估计其初始质量。先前的工作表明 II-P 和 II-L 超新星 (SNe) 具有红超巨星 (RSG) 前身，并且这些前身的初始质量范围似乎仅限于 $<$17M$_\odot$。这与进化模型预测的 25-30M$_\odot$ 的截止值形成鲜明对比，这一结果被称为“红超巨星问题”。在这里，我们研究了将爆炸前光度测量转换为初始质量时存在的系统误差的一个特定来源，即用于将单波段通量转换为测辐射热光度的测辐射热校正 (BC)。我们使用星团表明，当 RSG 接近 SN 时，RSG 会演化为较晚的光谱类型，这反过来又导致 BC 变得更大。如果不考虑这一点，就会导致系统性地低估恒星的光度，进而低估其初始质量。使用我们基于经验的 BC，我们重新评估了在爆炸前成像中检测到其祖细胞的 II-P 和 II-L 超新星。将初始质量函数拟合到这些更新的质量会导致质量上限增加 $M_{\rm hi}$=$19.0^{+2.5}_{-1.3}$M$_\odot$，95% 的置信上限为 $<$27M$_\odot$。考虑到质量-光度关系中的有限样本量效应和系统不确定性，将截止值提高到$M_{\rm hi}$=25M$_\odot$（$<$33M$_\odot$，95% 置信度）。因此，我们得出的结论是，目前没有强有力的证据表明核心塌陷超新星“缺失”了高质量祖细胞。
There are a growing number of nearby SNe for which the progenitor star is detected in archival pre-explosion imaging. From these images it is possible to measure the progenitor's brightness a few years before explosion, and ultimately estimate its initial mass. Previous work has shown that II-P and II-L supernovae (SNe) have Red Supergiant (RSG) progenitors, and that the range of initial masses for these progenitors seems to be limited to $<$17M$_\odot$. This is in contrast with the cutoff of 25-30M$_\odot$ predicted by evolutionary models, a result which is termed the 'Red Supergiant Problem'. Here we investigate one particular source of systematic error present in converting pre-explosion photometry into an initial mass, that of the bolometric correction (BC) used to convert a single-band flux into a bolometric luminosity. We show, using star clusters, that RSGs evolve to later spectral types as they approach SN, which in turn causes the BC to become larger. Failure to account for this results in a systematic underestimate of a star's luminosity, and hence its initial mass. Using our empirically motivated BCs we reappraise the II-P and II-L SNe that have their progenitors detected in pre-explosion imaging. Fitting an initial mass function to these updated masses results in an increased upper mass cutoff of $M_{\rm hi}$=$19.0^{+2.5}_{-1.3}$M$_\odot$, with a 95% upper confidence limit of $<$27M$_\odot$. Accounting for finite sample size effects and systematic uncertainties in the mass-luminosity relationship raises the cutoff to $M_{\rm hi}$=25M$_\odot$ ($<$33M$_\odot$, 95% confidence). We therefore conclude that there is currently no strong evidence for `missing' high mass progenitors to core-collapse SNe.