论文标题
ZTF对IA型超新星III的早期观察：早期颜色作为爆炸模型和多个种群的测试
ZTF Early Observations of Type Ia Supernovae III: Early-Time Colors as a Test for Explosion Models and Multiple Populations
论文作者
论文摘要
IA型超新星的颜色在爆炸后的头几天提供了不同模型之间的潜在判别。在本文中，我们介绍了$ G-R $颜色的65型IA类型超新星的颜色在2018年的Zwicky Transient设施的第5天内发现，该样本大约是文献中的三倍。我们发现，$ g-r $颜色在早期阶段本质上是均匀的，大约一半的分散归因于光度不确定性（$σ_\ mathrm {noings} \simσ_\simσ_\ mathrm {int} \ sim $ 0.18 mag）。颜色几乎不变，从初光后的6天开始（$ g-r \ sim-0.15 $ mag），而较早时期的时间演变的特征是连续的斜率范围，从迅速过渡到蓝色的事件（$ \ sim-0.25 $^$^$^$^$^$^{ - 1} $）到flater flater a flatter aflatter vertolution。 The continuum in the slope distribution is in good agreement both with models requiring some amount of $^{56}$Ni mixed in the outermost regions of the ejecta and with "double-detonation" models having thin helium layers ($M_\mathrm{He}=0.01\,M_\odot$) and varying carbon-oxygen core masses.同时，六个事件显示了具有较大氦气质量的“双重核”模型预测的独特的“红色颠簸”标志的证据。我们最终确定了早期$ g-r $斜率与超新星亮度之间的显着相关性，并且与颜色演变的更明亮的事件相关（p值= 0.006）。但是，斜率的分布与从一个人群中获取的分布是一致的，没有证据表明基于$ b-v $颜色的文献中所主张的两个组成部分。
Colors of Type Ia supernovae in the first few days after explosion provide a potential discriminant between different models. In this paper, we present $g-r$ colors of 65 Type Ia supernovae discovered within 5 days from first light by the Zwicky Transient Facility in 2018, a sample that is about three times larger than that in the literature. We find that $g-r$ colors are intrinsically rather homogeneous at early phases, with about half of the dispersion attributable to photometric uncertainties ($σ_\mathrm{noise}\simσ_\mathrm{int}\sim$ 0.18 mag). Colors are nearly constant starting from 6 days after first light ($g-r\sim-0.15$ mag), while the time evolution at earlier epochs is characterized by a continuous range of slopes, from events rapidly transitioning from redder to bluer colors (slope of $\sim-0.25$ mag day$^{-1}$) to events with a flatter evolution. The continuum in the slope distribution is in good agreement both with models requiring some amount of $^{56}$Ni mixed in the outermost regions of the ejecta and with "double-detonation" models having thin helium layers ($M_\mathrm{He}=0.01\,M_\odot$) and varying carbon-oxygen core masses. At the same time, six events show evidence for a distinctive "red bump" signature predicted by "double-detonation" models with larger helium masses. We finally identify a significant correlation between the early-time $g-r$ slopes and supernova brightness, with brighter events associated to flatter color evolution (p-value=0.006). The distribution of slopes, however, is consistent with being drawn from a single population, with no evidence for two components as claimed in the literature based on $B-V$ colors.
