An up-scattered cocoon emission model of Gamma-Ray Burst high-energy lags

Abstract

The Fermi Gamma-ray Space Telescope recently detected the most energetic gamma-ray burst so far, GRB 080916C, and reported its detailed temporal properties in an extremely broad spectral range: (i) the time-resolved spectra are well described by broken power-law forms over the energy range of $10\mathrm{keV}-10$ GeV, (ii) the high-energy emission (at $\epsilon >100$ MeV) is delayed by $\approx 5$s with respect to the $\epsilon \lesssim 1$ MeV emission, and (iii) the emission onset times shift towards later times in the higher energy bands. We show that this behavior of the high-energy emission can be explained by a model in which the prompt emission consists of two components: one is the emission component peaking at $\epsilon \sim 1$ MeV due to the synchrotron-self-Compton radiation of electrons accelerated in the internal shock of the jet and the other is the component peaking at $\epsilon \sim 100$ MeV due to up-scattering of the photospheric X-ray emission of the expanding cocoon (i.e., the hot bubble produced by dissipation of the jet energy inside the progenitor star) off the same electrons in the jet. Based on this model, we derive some constraints on the radius of the progenitor star and the total energy and mass of the cocoon of this GRB, which may provide information on the structure of the progenitor star and the physical conditions of the jet propagating in the star. The up-scattered cocoon emission could be important for other Fermi-GRBs as well. We discuss some predictions of this model, including a prompt bright optical emission and a soft X-ray excess.

emulateapj 16 pages, 5 figures, accepted version uploaded (no changes from v2). From v1, introduction and summary expanded, discussion on photospheric emission of jet (section 5.3) modified, discussion on other long and short GRBs (section 6) added

References in corpus (20)

• Discerning the physical origins of cosmological Gamma-ray bursts based on multiple observational criteria: the cases of z=6.7 GRB 080913, z=8.3 GRB 090423, and some short/hard GRBs
• Magnetic acceleration of ultra-relativistic jets in gamma-ray burst sources
• REM observations of GRB 060418 and GRB 060607A: the onset of the afterglow and the initial fireball Lorentz factor determination
• Time-Dependent Models of Accretion Disks Formed from Compact Object Mergers
• Asymptotic structure of Poynting dominated jets
• Evidence of an initially magnetically dominated outflow in GRB 080916C
• Very high efficiency photospheric emission in long duration gamma-ray bursts
• High Energy Afterglow from Gamma-ray Bursts
• The redshift and afterglow of the extremely energetic gamma-ray burst GRB 080916C
• Angular Energy Distribution of Collapsar-Jets
• Gamma-ray Burst 080319B: Evidence for Relativistic Turbulence, Not Internal Shocks
• Prompt Emission of High Energy Photons from Gamma Ray Bursts
• GRB 080916C: on the radiation origin of the prompt emission from KeV/MeV to GeV
• Collimated Jet or Expanding Outflow: Possible Origins of GRBs and X-Ray Flashes
• Expected high energy emission from GRB 080319B and origins of the GeV emission of GRBs 080514B, 080916C and 081024B
• Observational Limits on Inverse Compton Processes in GRBs
• Low angular momentum accretion in the collapsar: how long can a long GRB be?
• Interpretation and implication of the non-detection of GeV spectrum excess by Fermi gamma-ray Space Telescope in most GRBs
• GeV photons from up-scattering of supernova shock breakout X-rays by an outside GRB jet
• Technology Section of the White Paper on the Status and Future of Ground-based TeV Gamma-ray Astronomy

Cited by in corpus (48)

• The Physics of Gamma-Ray Bursts and Relativistic Jets
• The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
• A Comprehensive Analysis of Fermi Gamma-Ray Burst Data. I. Spectral Components and Their Possible Physical Origins of LAT/GBM GRBs
• A decade of Gamma-Ray Bursts observed by $Fermi$-LAT: The 2${}^{nd}$ GRB catalog
• Prospects for constraining quantum gravity dispersion with near term observations
• Open Questions in GRB Physics
• Gamma Ray Bursts
• A Photosphere-Internal Shock Model of Gamma-Ray Bursts: Case Studies of Fermi/LAT Bursts
• Three-Dimensional Simulations of MHD Turbulence Behind Relativistic Shock Waves and Their Implications for GRBs
• Gamma-Ray Burst Science in the Era of the Cherenkov Telescope Array
• Gamma Ray Bursts in the Swift-Fermi Era
• On the High Energy Emission of the Short GRB 090510
• GeV emission from a compact binary merger
• Thermal Radiation from GRB Jets
• A New Test of Lorentz Invariance Violation: the Spectral Lag Transition of GRB 160625B
• On the origin of GeV emission in gamma-ray bursts
• Do Fermi-LAT observations imply very large Lorentz factors in GRB outflows ?
• Gamma-Ray Burst Prompt Emission
• Modeling the broadband emission of Fermi/LAT GRB 090902B
• On the Implications of Late Internal Dissipation for Shallow-Decay Afterglow Emission and Associated High-Energy Gamma-Ray Signals
• Null fluid collapse in brane world models
• External Inverse-Compton Emission from Low-Luminosity Gamma-Ray Bursts: Application to GRB 190829A
• Spectral-Temporal Simulations of Internal Dissipation Models of Gamma-Ray Bursts
• Prompt X-ray and Optical Excess Emission due to Hadronic Cascades in Gamma-Ray Bursts
• Luminous supernova-like UV/optical/infrared transients associated with ultra-long gamma-ray bursts from metal-poor blue supergiants
• Prospects for Detecting Gamma-Ray Bursts at Very High Energies with the Cherenkov Telescope Array
• Photospheric Emission in Gamma-Ray Bursts
• Delayed Onset of High-Energy Emissions in Leptonic and Hadronic Models of Gamma-Ray Bursts
• The spectrum of Gamma-ray Burst: a clue
• High-energy emission as a test of the prior emission model for gamma-ray burst afterglows
• Gamma Ray Bursts
• Photon and Neutrino Spectra of Time-Dependent Photospheric Models of Gamma-Ray Bursts
• Upscattered Cocoon Emission in Short Gamma-ray Bursts as High-energy Gamma-ray Counterparts to Gravitational Waves
• Magnetic jet model for GRBs and the delayed arrival of >100 MeV photons
• Ultra-high Energy Cosmic Rays and Neutrinos from Gamma-Ray Bursts, Hypernovae and Galactic Shocks
• Spectral Lag Transition of 32 Fermi Gamma-ray Bursts and their Application on Constraining Lorentz Invariance Violation
• Early Thermal X-ray Emission from Long Gamma-ray Bursts and Their Circumstellar Environments
• The origin of very-high-energy gamma-rays from GRB 221009A: implications for reverse shock proton synchrotron emission
• Some Implications of inverse-Compton Scattering of Hot Cocoon Radiation by relativistic jets in Gamma-Ray Bursts
• Multiband Fitting to Three Long GRBs with Fermi/LAT Data: Structured Ejecta Sweeping up a Density-Jump Medium
• High-energy neutrino emission associated with gravitational-wave signals: effects of cocoon photons and constraints on late-time emission
• Self Organized Criticality in an one dimensional magnetized grid. Application to GRB X-ray afterglows
• Jitter Self-Compton Process: GeV Emission of GRB 100728A
• Broad band simulation of Gamma Ray Bursts (GRB) prompt emission in presence of an external magnetic field
• Relativistic Jets: Open Problems and Challenges
• Off-axis MeV and very-high-energy gamma-ray emissions from structured gamma-ray burst jets
• A Concept of Assessment of LIV Tests with THESEUS Using the Gamma-Ray Bursts Detected by Fermi/GBM
• Predicting Multiwavelength Emission Associated with X-Ray Flares and Extended Emission of Gamma-Ray Bursts