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

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 (Γ0 = 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.

20 pages, 3 figures, accepted for publication in ApJ

References in corpus (13)

• An online repository of Swift/XRT light curves of GRBs
• Gamma-Ray Bursts: Progress, Problems & Prospects
• REM observations of GRB 060418 and GRB 060607A: the onset of the afterglow and the initial fireball Lorentz factor determination
• The First Survey of X-ray Flares from Gamma Ray Bursts Observed by Swift: Spectral Properties and Energetics
• "Late prompt" emission in Gamma Ray Bursts?
• Taxonomy of GRB optical light-curves: identification of a salient class of early afterglows
• The Onset of Gamma-Ray Burst Afterglow
• Optical afterglows of Gamma-Ray Bursts: peaks, plateaus, and possibilities
• Multi-color Shallow Decay and Chromatic Breaks in the GRB 050319 Optical Afterglow
• Gamma-ray burst afterglows
• The Taiwanese-American Occultation Survey: The Multi-Telescope Robotic Observatory
• Testing the External Shock Model of Gamma-Ray Bursts using the Late-Time Simultaneous Optical and X-ray Afterglows
• Infrared/optical - X-ray simultaneous observations of X-ray flares in GRB 071112C and GRB 080506

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