The GRB 071112C: A Case Study of Different Mechanisms in X-ray and Optical Temporal Evolution

TL;DR

This study analyzes the differing temporal behaviors of X-ray and optical emissions in GRB 071112C, revealing distinct mechanisms and supporting the afterglow onset scenario for optical emission while suggesting additional processes for X-ray features.

Contribution

It demonstrates that X-ray and optical emissions in GRB 071112C originate from different mechanisms, challenging the external shock model and proposing alternative explanations for X-ray features.

Findings

Optical light curve shows initial rise and decay consistent with afterglow onset.

X-ray light curve exhibits a decay plus flare, indicating additional energy processes.

The optical flux is dominated by afterglow, while X-ray features suggest energy injection or internal dissipation.

Abstract

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.