On the Synchrotron Self-Compton Emission from Relativistic Shocks and Its Implications for Gamma-Ray Burst Afterglows

By R. Sari, A. Esin. 2000

407 citations recorded by the source corpus.

We consider the effects of inverse Compton scattering of synchrotron photons from relativistic electrons in γ-ray burst (GRB) afterglows. We compute the spectrum of the inverse Compton emission and find that it can dominate the total cooling rate of the afterglow for several months or even years after the initial explosion. We demonstrate that the presence of strong inverse Compton cooling can be deduced from the effect it has on the time evolution of the cooling break in the synchrotron spectral component, and therefore on the optical and X-ray afterglow light curves. We then show how the physical interpretation of the observed characteristics of the synchrotron spectrum must be modified to take into consideration this extra source of cooling and give a revised prescription for computing physical parameters characterizing the expanding shock wave from the observed quantities. We find that for a given set of observables (synchrotron break frequencies and fluxes) there is either no consistent physical interpretation or two of them. Finally we discuss the prospects of directly detecting the inverse Compton emission with Chandra. We argue that such a detection is possible for GRBs exploding in a reasonably dense (n ≳ 1 cm-3) medium.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4653e538818e76b8d918921785bd8a4fa079897f

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Citations in the corpus

FERMI OBSERVATIONS OF GRB 090510: A SHORT–HARD GAMMA-RAY BURST WITH AN ADDITIONAL, HARD POWER-LAW COMPONENT FROM 10 keV TO GeV ENERGIES (2010, background): “The SSC component is stronger for a large ratio of nonthermal electron to magnetic-field energy density, as expressed by the condition ǫe ≫ ǫB (Sari & Esin 2001; Zhang & Mészáros 2001), and also when the GRB has a lower bulk Lorentz factor for an external shock origin.”
The physics of gamma-ray bursts & relativistic jets (2014, background): “Second, the SSC introduces an extra spectral component at high energies which could dominate in the GeV band, and might show up in the X-ray band at late time if the ambient density is large [147,243,242,244].”
A Standard Kinetic Energy Reservoir in Gamma-Ray Burst Afterglows (2003, background): “The contribution from inverse Compton (IC) emission, which depends strongly on n0 and B (Sari & Esin 2001), is apparently not significant.”
High-Energy Spectral Components in Gamma-Ray Burst Afterglows (2001, methodology): “The cooling energy γc,x is defined by equating the comoving adiabatic expansion time t′ad ∼ r/(Γc) ∼ Γt (where Γ is the bulk Lorentz factor of the blastwave at the radius r, t ∼ Γ−2(r/c) is the expansion time in the observer frame) to the comoving radiation cooling time t′c = [(t ′ sy) −1 + (t′IC) −”
The size of the jet launching region in M87 (2011, background): “…and self-Compton components in a homogeneous blob with a power law distribution of electrons, ignoring all relativistic and viewing effects is (e.g., Sari & Esin 2001): νFν(IC) νFν(Syn) ∼ 2 3 p− 1 p+ 3 σT n R γ p−1 min γ 3−p max , (13) where σT is the Thompson cross-section and R is the size of…”
Reconciling observed gamma-ray burst prompt spectra with synchrotron radiation? (2010, background): “…well known that in Thomson egime (wm ≪ 1), as the electron cooling rate due to inverse Compton scatterings remains proportional toγ2 like for the synchrotron power, the spectral shape of the synchrotron component is un-affected by the scatterings (see e.g. Sari & Esin 2001; Bošnjak et al. 2009).”
Probing the cosmic reionization history and local environment of gamma‐ray bursts through radio dispersion (2003, background): “The Compton parameter Y is Y = ( √ 4ǫe/ǫB + 1 − 1)/2 if the electrons are fast cooling (γc < γm), while it decreases slowly with t if the electrons are slow cooling (γm < γc) (Sari & Esin 2001); we approximate by taking the fast cooling value at all times.”
On the generation of high-energy photons detected by the Fermi Satellite from gamma-ray bursts (2009, background): “…(such as the synchrotron-self-Compton process) or of an external origin e.g. Meszaros & Rees (1994), Pilla & Loeb (1998), Dermer et al. (2000), Sari & Esin (2001), Wang et al. (2001a, 2001b), Zhang & Meszaros (2001), Granot & Guetta (2003), Guetta & Granot (2003), Piran et al. (2004),…”
The Shape of Spectral Breaks in Gamma-Ray Burst Afterglows (2001, background): “This effect is know to be important, whenǫB ≪ ǫe (Sari, Narayan & Piran 1996, Panaitescu & Kumar 2000, Sari & Esin 2001).”
Theories of Gamma-Ray Bursts (2001, background): “Its effects on afterglows were considered by (Waxman 1997b), and observational manifestations in afterglows were investigated more carefully by Panaitescu & Kumar 2000 and Sari & Esin 2001.”
AFTERGLOW OBSERVATIONS OF FERMI LARGE AREA TELESCOPE GAMMA-RAY BURSTS AND THE EMERGING CLASS OF HYPER-ENERGETIC EVENTS (2010, methodology): “Instead, we construct afterglow models (including both the standard formulation and corrections for radiative losses and inverseCompton emission; Sari & Esin 2001) and compare these with our observations using the multi-parameter fitting program of Yost et al. (2003).”
The Cosmic Dispersion Measure from Gamma-Ray Burst Afterglows: Probing the Reionization History and the Burst Environment (2003, background): “Inverse Compton scattering may prolong the fast cooling regime (Sari & Esin 2001), in which an additional spectral segment may appear (Granot, Piran, & Sari11/8F ∝ nn 2000).”
Properties of Relativistic Jets in Gamma-Ray Burst Afterglows (2001, background): “GRB 000926 The X-ray emission (Piro et al. 2001) of this afterglow provided, for the first time, evidence (Harrison et al. 2001) that the X-ray emission may be inverse Compton scatterings (PK00; Sari & Esin 2001).”
A complete reference of the analytical synchrotron external shock models of gamma-ray bursts (2013, background): “The detailed treatments of the SSC effect 49 can be found in Sari and Esin (2001) and Gao et al. (2013).”
Gamma-Ray Bursts in the Swift Era (2007, background): “…produces significant GeV emission that is detectable by GLAST (e.g., Mészáros & Rees 1994; Dermer et al. 2000; Zhang & Mészáros 2001b, for more general discussion of SSC process in the external forward shock, see Wei & Lu 1998, 2000a; Panaitescu & Kumar 2000; Sari & Esin 2001; Wu et al 2005b).”
Short-hard gamma-ray bursts (2007, methodology): “3.1 of Sari & Esin 2001): Y ≡ LIC Lsyn = Usyn(ν < νKN [γc]) UB = ηradηKNUe (1 + Y )UB = ηradηKNεe (1 + Y )εB , (22) where Usyn, UB and Ue are the energy density of the synchrotron emitted photons, the magnetic field, and the relativistic electrons respectively (measured in the plasma rest frame).…”