标题： 两个在共同红移 z = 0.54 处的伽马射线暴超新星的故事 显示英文标题

标题： A tale of two GRB-SNe at a common redshift of z = 0.54

摘要： 我们展示了长持续时间伽玛射线暴（GRBs）060729和090618的地面和哈勃空间望远镜（HST）光学观测结果，两者的红移均为z = 0.54。 对于GRB 060729，在光学光变曲线（LCs）中观察到突起，而光学暂现源（OT）的晚期多波段能谱分布（SEDs）类似于本地类型Ic超新星（SNe）。 对于GRB 090618，我们光学观测的密集采样使我们能够检测到光学LCs中的明显突起以及颜色变化，这些变化表明光线来自核心坍缩超新星。 这两个事件的伴生超新星分别与SN1998bw（一个已知的伽玛射线暴-超新星）和SN1994I（一个没有已知伽玛射线暴对应体的典型类型Ic超新星）进行了比较，在两种情况下，亮度和时间演化更接近SN1998bw。 我们还利用了针对GRB 090618的广泛光学和射电数据，以及公开可用的SWIFT -XRT数据，并讨论了早期余辉的特性。 在简单的喷流模型背景下，GRB 090618的余辉最好由t-to > 0.5天的喷流中断来解释。 随后，我们将所有与伽玛射线暴和X射线闪光（XRF）相关的超新星的静止框架峰值V波段绝对星等与大量本地类型Ibc超新星进行比较，得出结论：当考虑宿主星系消光时，伽玛射线暴/XRF相关超新星的峰值星等无法与非伽玛射线暴/XRF超新星的峰值星等区分开来。 显示英文摘要

摘要： We present ground-based and HST optical observations of the optical transients (OTs) of long-duration Gamma Ray Bursts (GRBs) 060729 and 090618, both at a redshift of z = 0.54. For GRB 060729, bumps are seen in the optical light curves (LCs), and the late-time broadband spectral energy distributions (SEDs) of the OT resemble those of local type Ic supernovae (SNe). For GRB 090618, the dense sampling of our optical observations has allowed us to detect well-defined bumps in the optical LCs, as well as a change in colour, that are indicative of light coming from a core-collapse SN. The accompanying SNe for both events are individually compared with SN1998bw, a known GRB-supernova, and SN1994I, a typical type Ic supernova without a known GRB counterpart, and in both cases the brightness and temporal evolution more closely resemble SN1998bw. We also exploit our extensive optical and radio data for GRB 090618, as well as the publicly-available SWIFT -XRT data, and discuss the properties of the afterglow at early times. In the context of a simple jet-like model, the afterglow of GRB 090618 is best explained by the presence of a jet-break at t-to > 0.5 days. We then compare the rest-frame, peak V -band absolute magnitudes of all of the GRB and X-Ray Flash (XRF)-associated SNe with a large sample of local type Ibc SNe, concluding that, when host extinction is considered, the peak magnitudes of the GRB/XRF-SNe cannot be distinguished from the peak magnitudes of non-GRB/XRF SNe.