The GRB 071112C: A Case Study of Different Mechanisms in X-ray and   Optical Temporal Evolution
  We present the study on GRB 071112C X-ray and optical light curves. In these two wavelength ranges, we have found different temporal properties. The R-band light curve showed an initial rise followed by a single power-law decay, while the X-ray light curve was described by a single power-law decay plus a flare-like feature. Our analysis shows that the observed temporal evolution cannot be described by the external shock model in which the X-ray and optical emission are produced by the same emission mechanism. No significant color changes in multi-band light curves and a reasonable value of the initial Lorentz factor ({\Gamma}0 = 275 \pm 20) in a uniform ISM support the afterglow onset scenario as the correct interpretation for the early R-band rise. The result suggests the optical flux is dominated by afterglow. Our further investigations show that the X-ray flux could be created by an additional feature related to energy injection and X-ray afterglow. Different theoretical interpretations indicate the additional feature in X-ray can be explained by either late internal dissipation or local inverse-Compton scattering in the external shock. 
K. Y. Huang, Y. Urata, Y. H. Tung, H. M. Lin, L. P. Xin, M. Yoshida,   W. Zheng, C. Akerlof, S. Y. Wang, W. H. Ip, M. J. Leh...
astro-ph.HE astro-ph.CO