GRB Fermi-LAT afterglows: explaining flares, breaks, and energetic photons

Abstract

The Fermi-LAT collaboration presented the second gamma-ray burst (GRB) catalog covering its first 10 years of operations. A significant fraction of afterglow-phase light curves in this catalog cannot be explained by the closure relations of the standard synchrotron forward-shock model, suggesting that there could be an important contribution from another process. In view of the above, we derive the synchrotron self-Compton (SSC) light curves from the reverse shock in the thick- and thin-shell regime for a uniform-density medium. We show that this emission could explain the GeV flares exhibited in some LAT light curves. Additionally, we demonstrate that the passage of the forward shock synchrotron cooling break through the LAT band from jets expanding in a uniform-density environment may be responsible for the late time ($\approx 10^2$ s) steepening of LAT GRB afterglow light curves. As a particular case, we model the LAT light curve of GRB 160509A that exhibited a GeV flare together with a break in the long-lasting emission, and also two very high energy photons with energies of 51.9 and 41.5 GeV observed 76.5 and 242 s after the onset of the burst, respectively. Constraining the microphysical parameters and the circumburst density from the afterglow observations, we show that the GeV flare is consistent with a SSC reverse-shock model, the break in the long-lasting emission with the passage of the synchrotron cooling break through the Fermi-LAT band and the very energetic photons with SSC emission from the forward shock when the outflow carries a significant magnetic field ($R_{\mathrm{B}}\simeq 30$) and it decelerates in a uniform-density medium with a very low density ($n=4.554_{-1.121}^{+1.128}\times 10^{-4}\mathrm{c}{\mathrm{m}}^{-3}$).

arXiv comment19 pages, 5 figures. Accepted for publication in ApJ. New affiliations to the author list are added

References in corpus (81)

• Collapsars - Gamma-Ray Bursts and Explosions in "Failed Supernovae"
• Spectra and Light Curves of Gamma-Ray Burst Afterglows
• The Supernova -- Gamma-Ray Burst Connection
• Optical and Long Wavelength Afterglow from Gamma-Ray Bursts
• Visualization in Bayesian workflow
• Jets in GRBs
• The Physics of Gamma-Ray Bursts and Relativistic Jets
• Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data
• The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
• Gamma-Ray Bursts: Progress, Problems & Prospects
• On The Synchrotron Self-Compton Emission from Relativistic Shocks and Its Implications for Gamma-Ray Burst Afterglows
• Fermi Observations of GRB 090902B: A Distinct Spectral Component in the Prompt and Delayed Emission
• Analytic Light-Curves of Gamma-Ray Burst Afterglows: Homogeneous versus Wind External Media
• Afterglow Emission from Naked Gamma-Ray Bursts
• Fermi Observations of GRB 090510: A Short Hard Gamma-Ray Burst with an Additional, Hard Power-Law Component from 10 keV to GeV Energies
• GRB990123, The Optical Flash and The Fireball Model
• Hydrodynamic Time Scales and Temporal Structure of GRBs
• Gamma-Ray Burst Environments and Progenitors
• Light Curves of GRB Optical Flashes
• Gamma-ray burst early optical afterglows: implications for the initial Lorentz factor and the central engine
• Fermi-LAT Observations of the Gamma-ray Burst GRB 130427A
• Testing the standard fireball model of GRBs using late X-ray afterglows measured by Swift
• Gamma-ray burst early afterglows: reverse shock emission from an arbitrarily magnetized ejecta
• A decade of Gamma-Ray Bursts observed by $Fermi$-LAT: The 2${}^{nd}$ GRB catalog
• On the generation of high energy photons detected by the Fermi Satellite from gamma-ray bursts
• A Study of the Afterglows of Four GRBs: Constraining the Explosion and Fireball Model
• A Reconnection Switch to Trigger Gamma-Ray Burst Jet Dissipation
• The e-ASTROGAM mission (exploring the extreme Universe with gamma rays in the MeV-GeV range)
• Detection of a spectral break in the extra hard component of GRB 090926A
• External forward shock origin of high energy emission for three GRBs detected by Fermi
• GRB efficiency and Possible Physical Processes Shaping the Early Afterglow
• The Afterglow of GRB 130427A from 1 to 10^16 GHz
• GeV emission from Gamma Ray Bursts: a radiative fireball?
• Prompt GRB emission from gradual energy dissipation
• Evidence for chromatic X-ray light-curve breaks in Swift GRB afterglows and their theoretical implications
• The extragalactic background light revisited and the cosmic photon-photon opacity
• The Swift Burst Analyser I: BAT and XRT spectral and flux evolution of Gamma Ray Bursts
• Optical Flashes and Radio Flares in GRBs afterglow: Numerical Study
• Energies of GRB blast waves and prompt efficiencies as implied by modeling of X-ray and GeV afterglows
• A Reverse Shock in GRB 130427A
• Efficiency Crisis of Swift Gamma-Ray Bursts with Shallow X-ray Afterglows: Prior Activity or Time-Dependent Microphysics?
• Energy input and response from prompt and early optical afterglow emission in gamma-ray bursts
• On the sensitivity of the HAWC observatory to gamma-ray bursts
• Early Optical Afterglows from Wind-Type Gamma-Ray Bursts
• A Unified Treatment of the Gamma-Ray Burst 021211 and Its Afterglow Emissions
• Klein-Nishina effects on the high-energy afterglow emission of gamma-ray bursts
• The circumburst density profile around GRB progenitors: a statistical study
• Multiwavelength observations of GRB 110731A: GeV emission from onset to afterglow
• The Onset of Gamma-Ray Burst Afterglow
• Toward a standard Gamma Ray Burst: tight correlations between the prompt and the afterglow plateau phase emission
• Electrons' energy in GRB afterglows implied by radio peaks
• A Reverse Shock in GRB 160509A
• GRB 091127: The cooling break race on magnetic fuel
• Properties of GRB Lightcurves from Magnetic Reconnection
• Prompt Gamma Ray Burst emission from gradual magnetic dissipation
• Inverse Compton X-ray Flare from GRB Reverse Shock
• Analysis and modelling of the multi-wavelength observations of the luminous GRB 190114C
• Synchrotron self-Compton as a likely mechanism of photons beyond the synchrotron limit in GRB 190114C
• Theoretical Description Of GRB 160625B with Wind-to-ISM Transition and Implications for a Magnetized Outflow
• Is GeV Emission from Gamma-Ray Bursts of External Shock Origin?
• The emission mechanism in magnetically dominated GRB outflows
• A Reverse Shock in GRB 181201A
• A Reverse Shock and Unusual Radio Properties in GRB 160625B
• The spectral-temporal properties of the prompt pulses and rapid decay phase of GRBs
• Modeling the early multiwavelength emission in GRB130427A
• Modeling the observations of GRB 180720B: From radio to sub-TeV gamma-rays
• Marginally fast cooling synchrotron models for prompt GRBs
• Gamma-Ray Bursts at high and very high energies
• Single- and Two-Component GRB Spectra in the Fermi GBM-LAT Energy Range
• Gamma-ray burst afterglow scaling relations for the full blast wave evolution
• GRB 110731A: Early afterglow in stellar wind powered by a magnetized outflow
• Modeling the early afterglow in the short and hard GRB 090510
• Electron Heating by the Ion Cyclotron Instability in Collisionless Accretion Flows. II. Electron Heating Efficiency as a Function of Flow Conditions
• Closure relations of Gamma Ray Bursts in high energy emission
• Reverse Shock Emission Revealed in Early Photometry in the Candidate Short GRB 180418A
• Radiative striped wind model for gamma-ray bursts
• The origin of the optical flashes: The case study of GRB 080319B and GRB 130427A
• Properties of the Affine Invariant Ensemble Sampler in high dimensions
• Late X-ray flares from the interaction of a reverse shock with a stratified ejecta in GRB afterglows: simulations on a moving mesh
• An evolving GeV spectrum from prompt to afterglow: the case of GRB 160509A
• "Self-absorbed" GeV light-curves of Gamma-Ray Burst afterglows

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