AI 中文总结
研究 Ia 型超新星光变曲线早期过剩问题，采用幂律和 SALT2 拟合、对比双爆及伴星相互作用模型两种方法，识别出 17 个可靠候选者，分析其特征及在不同模型下情况，未明确早期流量过剩起源。
AI 中文摘要
人们普遍认为 Ia 型超新星（SNe Ia）是双星系统中碳/氧白矮星（WDs）的热核爆炸，但其前身星和爆炸机制仍不确定。其最早的光变曲线探测最外层抛射物并为爆炸提供重要约束。我们分析 ZTF DR2 的 Ia 型超新星样本以寻找早期流量过剩的物体（EEx SNe Ia）。采用两种互补方法：一是通过幂律和 SALT2 拟合识别无早期过剩模型的偏差；二是将观测与双爆（DD）和伴星相互作用（CI）模型比较。两种方法分别识别出 145 和 199 个候选者，虽在所选对象和候选者总数上有很大分歧。综合所有方法，识别出 17 个可靠的 EEx SNe Ia 候选者，包括 6 个超亮事件。最强过剩达到峰值流量的约 10% - 17%。最佳候选者平均伸展更高，优先出现在低质量、更蓝的宿主星系。估计 EEx SNe Ia 占所有 SNe Ia 的比例小于等于 25%，与之前工作一致，超亮亚型相对发生率高于正常 SNe Ia。在 DD 模型中，首选解决方案倾向于中等 WD 核心质量（1 M⊙）、低壳燃烧分数（20%）和更重的氦燃烧产物（56Ni），而 CI 模型无明显参数趋势。总体而言，没有令人信服的证据表明哪种情况是观测到的早期流量过剩的起源。
英文摘要
There is broad consensus that Type Ia supernovae (SNe Ia) are the thermonuclear explosions of C/O white dwarfs (WDs) in binary systems, but their progenitors and explosion mechanisms remain uncertain. Their earliest light curves probe the outermost ejecta and provide important constraints on the explosion. We analyse the ZTF DR2 sample of SNe Ia to search for objects exhibiting early flux excess (EEx SNe Ia). We employ two complementary approaches: (i) identifying deviations from models without early excess using power-law and SALT2 fits, and (ii) comparing observations with double-detonation (DD) and companion-interaction (CI) models. The latter identify 145 and 199 candidates, respectively, although the methods disagree substantially on both the objects selected and the total number of candidates. Combining all methods, we identify 17 robust EEx SN Ia candidates, including six over-luminous events (five 91T-like and one 03fg-like). The strongest excesses reach ${\sim}10$--17\% of the peak flux. The best candidates have, on average, higher stretch and preferentially occur in lower-mass, bluer host galaxies, suggesting younger stellar populations. We estimate that EEx SNe Ia comprise $\lesssim25\%$ of all SNe Ia, consistent with previous work, with over-luminous subtypes showing a higher relative incidence than normal SNe Ia. Among the DD models, the preferred solutions favour intermediate WD core masses ($1 M_{\odot}$), low shell-burning fractions ($20\%$), and heavier He-burning products ($^{56}$Ni), whereas the CI models show no clear parameter trends. Overall, we find no compelling evidence that either scenario is preferred as the origin of the observed early flux excesses.
CommentsAccepted in A&A. 14+8 pages, 12+11 figures. Abstract edited due to Arxiv's characters limit
