부산대학교 도서관

In Hubble Space Telescope (HST) imaging taken on 2014 November 10, four images of supernova (SN) Refsdal(redshift z1.49) appeared in an Einstein-cross-like configuration (images S1S4) around an early-type galaxy in the cluster MACS J1149.5+2223 (z0.54). Almost all lens models of the cluster have predicted that the SN should reappear within a year in a second host-galaxy image created by the clusters potential. In HST observations taken on 2015 December 11, we find a new source at the predicted position of the new image of SN Refsdal approximately 8 from the previous images S1S4. This marks the first time the appearance of a SN at a particular time and location in the sky was successfully predicted in advance! We use these data and the light curve from the first four observed images of SN Refsdal to place constraints on the relative time delay and magnification of the new image (SX) compared to images S1S4. This enables us, for the first time, to test blind lens model predictions of both magnifications and time delays for a lensed SN. We find that the timing and brightness of the new image are consistent with the blind predictions of a fraction of the models. The reappearance illustrates the discriminatory power of this blind test and its utility to uncover sources of systematic uncertainty. From planned HST photometry, we expect to reach a precision of 12 on the time delay between S1S4 and SX.