@article{oai:sucra.repo.nii.ac.jp:00012964,
 author = {浦田, 裕次 and Yamazaki, Ryo and Sakamoto, Takanori and Huang, Kuiyun and Zheng, Weikang and Sato, Goro and Aoki, Tsutomu and Deng, Jinsong and Ioka, Kunihito and Ip, WingHuen and Kawabata, Koji S. and Lee, YiHsi and Xin, Liping and Mito, Liping and Miyata, Takashi and Nakada, Yoshikazu and Ohsugi, Takashi and Qiu, Yulei and Soyano, Takao and Tarusawa, Kenichi and 田代, 信 and Uemura, Makoto and Wei, Jianyan and Yamashita, Takuya},
 issue = {2},
 journal = {The Astrophysical Journal Letters},
 month = {},
 note = {We study the "normal" decay phase of the X- ray afterglows of gamma- ray bursts ( GRBs), which follows the shallow decay phase, using the events simultaneously observed in the R band. The classical external- shock model - in which neither the delayed energy injection nor time dependency of shock microphysics is considered shows that the decay indices of the X- ray and R- band light curves, alpha(x) and alpha(o), obey a certain relation, and that in particular, alpha(o) - alpha(x) should be larger than -1/4 unless the ambient density increases with the distance from the central engine. For our selected 14 samples, we have found that four events violate the limit at more than the 3 sigma level, so that a fraction of events are outliers of the classical external-shock model at the "normal" decay phase., text, application/pdf},
 pages = {L95--L98},
 title = {Testing the External-Shock Model of Gamma-Ray Bursts Using the Late-Time Simultaneous Optical and X-Ray Afterglows},
 volume = {668},
 year = {2007},
 yomi = {ウラタ, ユウジ and タシロ, マコト}
}