发表机构
Alikhanian National Science Laboratory; Institut d’Astrophysique de Paris (UMR 7095: CNRS and Sorbonne Université); School of Physics, Trinity College Dublin; Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto; Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto; Institute of Physics, Yerevan State University（阿利哈尼安国家科学实验室; 巴黎天体物理研究所; 都柏林圣三一学院物理学院; 波尔图大学空间与天体物理研究所; 波尔图大学理学院物理与天文系; 埃里温国立大学物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用354个近邻Ia型超新星样本，发现此前报道的速度子群环境差异主要由巡天选择效应导致，认为爆炸不对称性和观测角效应是速度多样性的重要来源。
AI 中文摘要
Ia型超新星（SNe Ia）在近极大光度时Si II λ6355的速度多样性的起源仍不确定。此前研究认为，高速度（HV）和正常速度（NV）的Ia型超新星处于系统上不同的宿主星系环境中，暗示其前身星群体存在差异。我们利用包含239个正常速度和115个高速度事件的354个近邻（z≤0.04）光谱学正常Ia型超新星样本重新检验该假说，这些样本来自定向和非定向巡天。对每个超新星，我们确定其宿主星系的形态、银心距和物理尺寸，获得一致的恒星质量估计，同时评估巡天选择效应的影响。Si II速度分布可由两个高斯分量很好地描述，证实了正常速度和高速度群体的存在。我们发现两个速度子群的银心距、宿主星系尺寸或恒星质量分布之间无统计学显著差异。此前研究报道的环境趋势仅在定向子样本中以边缘统计学显著性被恢复，而在非定向子样本中几乎完全消失，这与巡天选择效应在之前推断的正常速度和高速度事件的环境差异中起主要作用一致。我们的结果削弱了“观测到的Si II速度多样性主要由此处检验的全局宿主属性的系统差异驱动”的解释，转而支持“内禀爆炸不对称性和观测角效应解释了观测到的速度多样性的很大一部分”的情景，同时不排除局部环境条件或前身星属性可能的贡献。
英文摘要
The origin of the near-maximum-light Si II $λ$6355 velocity diversity among supernovae Ia (SNe Ia) remains uncertain. Previous studies have suggested that high-velocity (HV) and normal-velocity (NV) SNe Ia occupy systematically different host galaxy environments, implying differences in their progenitor populations. We re-examine this hypothesis using a sample of 354 nearby ($z\leq0.04$) spectroscopically normal SNe Ia, comprising 239 NV and 115 HV events, identified in targeted and untargeted surveys. For each SN, we determine the host galaxy morphology, galactocentric distance, and physical size, and obtain homogeneous stellar mass estimates while assessing the influence of survey-selection effects. The Si II velocity distribution is well described by two Gaussian components, confirming the NV and HV populations. We find no statistically significant differences between the galactocentric distance, host galaxy size, or stellar mass distributions of the two velocity subgroups. The environmental trends reported in previous studies are recovered only with marginal statistical significance in the targeted subsample, whereas they disappear almost entirely in the untargeted subsample, consistent with survey-selection effects playing a major role in the previously inferred environmental differences between the NV and HV events. Our results weaken the interpretation that the observed Si II velocity diversity is primarily driven by systematic differences in the global host properties examined here. Instead, they favour a scenario in which intrinsic explosion asymmetries and viewing-angle effects account for a substantial fraction of the observed velocity diversity, without excluding a possible contribution from local environmental conditions or progenitor properties.
Comments16 pages, 6 figures, 9 tables, online data, resubmitted to MNRAS after addressing referee's comments
