Synchrotron self-Compton Reverse Shock in Energy-Injection and Radiative Scenarios

Abstract

Gamma-ray bursts (GRBs) are among the most energetic extragalactic transients, providing a unique laboratory to investigate the physical origin of the diverse morphologies observed in high-energy light curves and spectra. These morphologies, interpreted through synchrotron and synchrotron self-Compton (SSC) closure relations (CRs), may depend on the circumburst density profile, energy injection, and the dynamical evolution of the reverse shock in the adiabatic or radiative regime. We derive the SSC closure relations produced in the reverse-shock region for both thick- and thin-shell cases, considering constant-density and stratified circumburst media. The analysis assumes two power-law (PL) distributions for the electron spectral index and includes scenarios with and without energy injection from the progenitor. We show that, depending on the physical parameters, SSC emission from the reverse shock can reproduce the initial steep-decay and plateau phases commonly observed in GRB afterglows. We then compare the predicted spectral and temporal indices with those derived from PL and broken power-law (BPL) fits reported in the Second Fermi-LAT Gamma-ray Burst Catalog (2FLGC). Our results indicate that PL (BPL) light-curve fits preferentially favor scenarios with (without) energy injection. In scenarios with energy injection, the data preferentially support a constant-density environment over a stellar-wind profile.

43 pages, 7 tables, 13 figures. The Astrophysical Journal, Volume 1006, Issue 2, id.227

References in corpus (23)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Multi-messenger Observations of a Binary Neutron Star Merger
• X-Ray Flares from Postmerger Millisecond Pulsars
• GRB Radiative Efficiencies Derived from the Swift Data: GRBs vs. XRFs, Long vs. Short
• The First Survey of X-ray Flares from Gamma Ray Bursts Observed by Swift: Temporal Properties and Morphology
• A decade of Gamma-Ray Bursts observed by $Fermi$-LAT: The 2${}^{nd}$ GRB catalog
• Klein-Nishina Effects on Optically Thin Synchrotron and Synchrotron Self-Compton Spectrum
• Gamma-Ray Burst Afterglows as Probes of Environment and Blastwave Physics II: the Distribution of p and Structure of the Circumburst Medium
• Analysis and modelling of the multi-wavelength observations of the luminous GRB 190114C
• Swift GRB Afterglows and the Forward-Shock Model
• On the Existence of the Plateau Emission in High-Energy Gamma-Ray Burst LightCurves observed byFermi-LAT
• A two component jet model for the X-ray afterglow flat segment in short GRB 051221A
• Closure relations during the plateau emission of Swift GRBs and the fundamental plane
• Afterglows from precursors in Gamma Ray Bursts. Application to the optical afterglow of GRB 091024
• Closure relations of Gamma Ray Bursts in high energy emission
• Flares in Gamma Ray Bursts: Disc Fragmentation and Evolution
• Observations of the Optical Afterglow of GRB 050319 : Wind to ISM transition in view
• GRB 140102A: Insight into Prompt Spectral Evolution and Early Optical Afterglow Emission
• GRB 180620A: Evidence for late-time energy injection
• Late Central Engine Activity in GRB 180205A
• Giant X-ray and optical Bump in GRBs: evidence for fall-back accretion model
• Hard Electron Energy Distribution in the Relativistic Shocks of GRB Afterglows
• Closure Relations of Synchrotron Self-Compton in Afterglow stratified medium and Fermi-LAT Detected Gamma-Ray Bursts