An External Shock Origin of GRB $\text{141028A}$

Abstract

The prompt emission of the long, smooth, and single-pulsed gamma-ray burst, GRB $\text{141028A}$, is analyzed under the guise of an external shock model. First, we fit the $\gamma$-ray spectrum with a two-component photon model, namely synchrotron+blackbody, and then fit the recovered evolution of the synchrotron $\nu F_{\nu }$ peak to an analytic model derived considering the emission of a relativistic blast-wave expanding into an external medium. The prediction of the model for the $\nu F_{\nu }$ peak evolution matches well with the observations. We observe the blast-wave transitioning into the deceleration phase. Further we assume the expansion of the blast-wave to be nearly adiabatic, motivated by the low magnetic field deduced from the observations. This allows us to recover within an order of magnitude the flux density at the $\nu F_{\nu }$ peak, which is remarkable considering the simplicity of the analytic model. Across all wavelengths, synchrotron emission from a single forward shock provides a sufficient solution for the observations. Under this scenario we argue that the distinction between $\text{prompt}$ and $\text{ afterglow}$ emission is superfluous as both early and late time emission emanate from the same source. While the external shock model is clearly not a universal solution, this analysis opens the possibility that at least some fraction of GRBs can be explained with an external shock origin of their prompt phase.

References in corpus (6)

• An online repository of Swift/XRT light curves of GRBs
• The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
• A new method of determining the initial size and Lorentz factor of gamma-ray burst fireballs using a thermal emission component
• The Energy-Dependence of GRB Minimum Variability Timescales
• Uncovering the Intrinsic Variability of Gamma-ray Bursts
• Monte Carlo simulations of the photospheric emission in GRBs

Cited by in corpus (20)

• A decade of Gamma-Ray Bursts observed by $Fermi$-LAT: The 2${}^{nd}$ GRB catalog
• Bulk Lorentz factors of Gamma-Ray Bursts
• On the origin of the multi-GeV photons from the closest burst with intermediate luminosity: GRB 190829A
• Clustering of gamma-ray burst types in the Fermi-GBM catalogue: indications of photosphere and synchrotron emissions during the prompt phase
• What can we learn from "internal plateaus"? The peculiar afterglow of GRB 070110
• The Fraction of Gamma-ray Bursts with an Observed Photospheric Emission Episode
• Is Spectral Width a Reliable Measure of GRB Emission Physics?
• Classification of Photospheric Emission in Short GRBs
• Inverse Compton Signatures of Gamma-Ray Burst Afterglows
• On the $\alpha$-Intensity Correlation in Gamma-Ray Bursts: Subphotospheric Heating with Varying Entropy
• Testing a model for subphotospheric dissipation in GRBs: fits to Fermi data constrain the dissipation scenario
• GRB120729A: external shock origin for both the prompt gamma-ray emission and afterglow
• Off-axis synchrotron light curves from full-time-domain moving-mesh simulations of jets from massive stars
• Investigating subphotospheric dissipation in gamma-ray bursts using joint Fermi-Swift observations
• Gravitational wave observations may constrain gamma-ray burst models: the case of GW 150914 - GBM
• GRB 200829A: External Shock Origin of the Very Early Prompt Emission?
• Lorentz Factor Evolution of an Expanding Jet Shell Observed in Gamma-ray Burst: Case study of GRB 160625B
• Is magnetically dominated outflow required to explain GRBs?
• The Rest-Frame Golenetskii Correlation via a Hierarchical Bayesian Analysis
• Jets in a Gamma-Ray Burst During its Prompt Emission: Evolution of Lorentz Factor