Photospheric signatures imprinted on the gamma-ray burst spectra

Abstract

A solution is presented for the spectrum of high-energy gamma-ray burst photons confined to a quasi-thermal baryonic photosphere. The solution is valid in the steady-state limit assuming the region under consideration is optically thick to the continuously injected photons. It is shown that for a high luminosity photosphere, the non-thermal electrons resulting from gamma-ray Compton cooling lose their energy by upscattering the soft thermalised radiation. The resulting spectral modifications offer the possibility of diagnosing not only the burst comoving luminosity but also the baryon load of the ejecta. This model leads to a simple physical interpretation of X-ray rich bursts and anomalous low-energy slopes.

7 pages, 3 figures; to appear in MNRAS pink pages

References in corpus (7)

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• The observable effects of a photospheric component on GRB's and XRF's prompt emission spectrum
• Identification and properties of the photospheric emission in GRB090902B
• Prompt emission spectra from the photosphere of a GRB
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• Observational evidence of dissipative photospheres in gamma-ray bursts
• Swift and XMM-Newton Observations of the Extraordinary GRB 060729: An afterglow with a more than 100 days X-ray light curve
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• Unstable GRB photospheres and electron-positron annihilation lines
• Gamma Ray Burst Prompt correlations
• Statistical Study of the Swift X-ray Flash and X-ray Rich Gamma-Ray Bursts
• Gamma-Ray Burst Precursors as the Remnant of the Thermal Radiation Initially Trapped in the Fireball
• An external-shock origin of the E_p-E_gamma relation for Gamma-Ray Bursts
• GRB 990413: Insight into the thermal phase evolution
• Subphotospheric emission from short gamma-ray bursts: Protons mold the multi-messenger signals
• Magnetized Shocks Mediated by Radiation from Leptonic and Hadronic Processes