Cooke Jeff, Sullivan Mark, Barton Elizabeth J, Bullock James S, Carlberg Ray G, Gal-Yam Avishay, Tollerud Erik
Center for Cosmology, Department of Physics and Astronomy, University of California, Irvine, California 92697-4574, USA.
Nature. 2009 Jul 9;460(7252):237-9. doi: 10.1038/nature08082.
Supernovae have been confirmed to redshift z approximately 1.7 (refs 1, 2) for type Ia (thermonuclear detonation of a white dwarf) and to z approximately 0.7 (refs 1, 3-5) for type II (collapse of the core of the star). The subclass type IIn (ref. 6) supernovae are luminous core-collapse explosions of massive stars and, unlike other types, are very bright in the ultraviolet, which should enable them to be found optically at redshifts z approximately 2 and higher. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z approximately 2 for 3-5 years after explosion (ref. 14). Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in archival data using a method designed to exploit these properties at z approximately 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured stellar initial mass function, but not with an evolving initial mass function proposed to explain independent observations at low and high redshift.
Ia型超新星（白矮星的热核爆炸）已被证实红移量z约为1.7（参考文献1、2），II型超新星（恒星核心坍缩）的红移量z约为0.7（参考文献1、3 - 5）。IIn型（参考文献6）超新星是大质量恒星的发光核心坍缩爆炸，与其他类型不同，它们在紫外波段非常明亮，这使得它们在红移量z约为2及更高时能够通过光学手段被发现。此外，抛射物质与星周物质的相互作用产生了强烈且持久的发射线，使得在爆炸后3 - 5年内，能够通过光谱确认许多此类在红移量z约为2的事件（参考文献14）。在此，我们报告在存档数据中利用一种旨在探测红移量z约为2时这些特性的方法检测到的三颗经光谱确认的IIn型超新星，其红移量分别为z = 0.808、2.013和2.357。IIn型超新星直接探测高红移处大质量恒星的形成。迄今为止发现的数量与本地测量的恒星初始质量函数的预期相符，但与为解释低红移和高红移处独立观测结果而提出的演化初始质量函数不相符。
