Shallow decay phase of X-ray afterglows

R. Sato*, K. Ioka, K. Toma, T. Nakamura, J. Kataoka, N. Kawai, T. Takahashi


研究成果: Conference contribution

1 被引用数 (Scopus)


We investigated the characteristics of the shallow decay phase in the early X-ray afterglows of GRBs observed by Swift X-Ray Telescope (XRT) during the period of January 2005 to December 2006. We found that the intrinsic break time at the shallow-to-normal decay transition in the X-ray light curve T brk0 is moderately well correlated with the isotropic X-ray luminosity in the end of the shallow decay phase (LX,end) as Tbrk0=(9.39±0.64)×103s(L X,end/1047ergsṡs-1) -0.71±0.03. Using Tbrk0-L X,end relation we have determined the pseudo redshifts of 33 GRBs. We compared the pseudo redshifts of 11 GRBs with measured redshifts and found the rms error to be 0.17 in logz. From this pseudo redshift, we estimate that ∼15% of the Swift GRBs have z>5. The advantages of this distance indicator is that (1) it requires only X-ray afterglow data while other methods such as Amati and Yonetoku correlations require the peak energy (Ep) of the prompt emission, (2) the redshift is uniquely determined without redshift degeneracies unlike the Amati correlation, and (3) the redshift is estimated in advance of deep follow-ups so that possible high redshift GRBs might be selected for detailed observations.

ホスト出版物のタイトルGamma-Ray Bursts 2007 - Proceedings of the Santa Fe Conference
出版ステータスPublished - 2008 12月 1
イベントSanta Fe Conference on Gamma-Ray Bursts 2007, GRB 2007 - Santa Fe, NM, United States
継続期間: 2007 11月 52007 11月 9


名前AIP Conference Proceedings


ConferenceSanta Fe Conference on Gamma-Ray Bursts 2007, GRB 2007
国/地域United States
CitySanta Fe, NM

ASJC Scopus subject areas

  • 物理学および天文学(全般)


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