The Study of The Early X-ray Afterglows About Bright and Dark GRBs

A systematic study on the X-ray afterglows of the optically dark and bright gamma-ray bursts is presented.Our results show that the distribution of the X-ray, the γ-ray of the dark GRBs and bright GRBs are similar, any observed differences should be caused by simply statistical fluctuation.These results indicated that the suppression of optical emission in the dark GRBs should result in the circumambiency, not in their central engine.