Multiple Sub-Jet Model of Gamma Ray Bursts and Possible Origin of X-ray Precursors and Post-cursors

Abstract

We assume that internal shocks of Gamma Ray Bursts (GRBs) consist of multiple sub-jets with a collimation half-angle $\sim \mathrm{several}\times {\gamma }_i^{-1}$, where ${\gamma }_i$ is the Lorenz factor of each sub-jet. If by chance a sub-jet is first emitted off-axis from the line of sight, the observed peak energy can be in the X-ray region. Next if by chance a subsequent sub-jet is emitted along the line of sight, then the peak energy will be in the gamma ray region and the gamma ray may arrive after the X-ray precursor from the former sub-jet depending on parameters. This model predicts a new class of GRBs with extremely weak and short gamma ray emission but X-ray precursor and/or post-cursor as well as an afterglow.

6 pages, Latex, accepted for publication in Astrophysical Journal Letters

References in corpus (7)

• Optical and Radio Observations of the Afterglow from GRB990510: Evidence for a Jet
• BVRI Observations of the Optical Afterglow of GRB 990510
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• GRB 061121: Broadband spectral evolution through the prompt and afterglow phases of a bright burst
• A Unified Model of Short and Long Gamma-Ray Bursts, X-Ray Rich Gamma-Ray Bursts, and X-Ray Flashes
• Collimated Jet or Expanding Outflow: Possible Origins of GRBs and X-Ray Flashes
• Shallow Decay of Early X-ray Afterglows from Inhomogeneous Gamma-Ray Burst Jets
• Ep-Eiso Correlation in a Multiple Subjet Model of Gamma-Ray Bursts
• The afterglow and complex environment of the optically dim burst GRB 980613
• Tail Emission of Prompt Gamma-Ray Burst Jets
• Short and Long GRBs: same emission mechanism?
• Multi-color Shallow Decay and Chromatic Breaks in the GRB 050319 Optical Afterglow
• Possible Origin of Lognormal Distributions in Gamma-Ray Bursts
• Delayed Flashes from Counter Jets of Gamma Ray Bursts
• Very early multi-color observations of the plateau phase of GRB 041006 afterglow
• A Possible Origin of Bimodal Distribution of Gamma-Ray Bursts
• Probing the Structure of Gamma-Ray Burst Jets with Steep Decay Phase of their Early X-ray Afterglows
• Unveiling the nature of the Einstein Probe transient EP 241021a
• Plasma Pressure Driven Asymmetric Supernovae and Highly Collimated Gamma-Ray Bursts