挑战主流塌缩星模型：在两个邻近的长伽玛暴源中并没有发现超新星

astro-ph/0608313 [abs, pdf] :

Title: A new type of massive stellar death: no supernovae from two nearby long gamma ray bursts

Comments: Submitted to Nature on July 7. Posted on Nature website July 12, see this http URL Revised on August 10

It is now accepted that long duration gamma-ray bursts (GRBs) are produced during the collapse of a massive star. The prevailing model (the collapsar) predicts that a broad-lined and luminous Type Ic core-collapse supernova (SN) accompanies every long-duration GRB. This association has been confirmed in observations of several nearby GRBs. Here we present observations of two nearby long-duration GRBs that challenge the prevailing model. In the GRBs 060505 and 060614 we demonstrate that no SN emission accompanied these bursts, down to limits hundreds of times fainter than the archetypal SN 1998bw that accompanied GRB 980425, and fainter than any Type Ic SN ever observed. Multi-band observations of the early afterglows, as well as spectroscopy of the GRB 060505 host galaxy, exclude the possibility of significant dust obscuration. Both GRBs are long-duration bursts, and we show that they lie in actively star-forming regions, typical of long GRBs. The absence of a SN to such deep limits is qualitatively different from all previous nearby long GRBs and suggests a new phenomenological type of massive stellar death.

译文：
当前，关于长暴（long GRB）起源于大质量恒星塌缩的观点被广为接受。其主流模型（塌缩星模型）预言每个长暴都会伴随着一个明亮的Ic型中心塌缩超新星（SN）。这种关联被几个邻近的伽玛暴所证实。
这里，我们给出两个邻近的长暴，其观测结果对以上的主流模型提出了挑战。在GRBs 060505 和 060614中，我们发现其中并没有SN的辐射成分。对早期余辉的多波段观测，以及对GRB 060505的寄主星系的光谱分析，都排除了明显的尘埃遮光效应。这两个伽玛暴都是长暴，并且发现他们都位于活动的恒星形成区，是典型的长暴。SN成分的缺失表明他们不同于以前的邻近长暴，可能预示着一类新型的大质量恒星塌缩模式。