SNe Iax Data

Type Iax supernovae (SNe Iax) are the most common class of peculiar SNe. While they are thought to be thermonuclear white-dwarf (WD) SNe, SNe Iax are observationally similar to, but distinct from SNe Ia. Unlike SNe Ia, where roughly 30\% occur in early-type galaxies, only one SN Iax has been discovered in an early-type galaxy, suggesting a relatively short delay time and a distinct progenitor system. Furthermore, one SN Iax progenitor system has been detected in pre-explosion images with its properties consistent with either of two models: a short-lived (<100 Myr) progenitor system consisting of a WD primary and a He-star companion, or a singular Wolf-Rayet progenitor star. Using deep Hubble Space Telescope images of nine nearby SN Iax host galaxies, we measure the properties of stars within 200 pc of the SN position. The ages of local stars, some of which formed with the SN progenitor system, can constrain the time between star formation and SN, known as the delay time. We compare the local stellar properties to synthetic photometry of single-stellar populations, fitting to a range of possible delay times for each SN. With this sample, we uniquely constrain the delay-time distribution for SNe~Iax, with a median and 1-sigma confidence interval delay time of 63 - 15 + 58 million years. The measured delay-time distribution provides an excellent constraint on the progenitor system for the class, indicating a preference for a WD progenitor system over a Wolf-Rayet progenitor star.

IaX型超新星（SNe Iax）是最常见的一类特殊超新星。尽管它们被归类为热核白矮星（WD）超新星，但IaX型超新星在观测特征上与Ia型超新星相似却又泾渭分明。与约30%的Ia型超新星诞生于早型星系不同，迄今仅在早型星系中发现过一例IaX型超新星，这暗示其延迟时间相对较短，且拥有独特的前身星系统。此外，研究人员已在暴前图像中探测到一个IaX型超新星的前身星系统，其性质符合两种模型之一：一种是由主序白矮星（WD）与氦星伴星组成的短寿命（<100百万年）前身星系统，另一种则为单一的沃尔夫-拉叶（Wolf-Rayet）前身星。本研究借助哈勃空间望远镜（Hubble Space Telescope）对9个邻近IaX型超新星宿主星系拍摄的深场图像，测量了超新星位置周边200秒差距（pc）内的恒星性质。这些局部恒星的年龄（其中部分恒星与该超新星的前身星系统同期形成）可用于限定恒星形成至超新星爆发之间的时间间隔，即所谓的延迟时间。我们将局部恒星的观测性质与单星族的合成测光结果进行对比，并为每一例超新星拟合一系列可能的延迟时间。基于本次样本，我们为IaX型超新星的延迟时间分布提供了独特的约束：其中位数延迟时间为63百万年，1σ置信区间为63（-15，+58）百万年。本次测得的延迟时间分布为该类超新星的前身星系统提供了强有力的限定，结果更倾向于支持白矮星前身星系统，而非沃尔夫-拉叶前身星模型。