Photosphere emission from a hybrid relativistic outflow with arbitrary dimensionless entropy and magnetization in GRBs

Abstract

In view of the recent Fermi observations of GRB prompt emission spectra, we develop a theory of photosphere emission of a hybrid relativistic outflow with a hot fireball component (defined by dimensionless entropy $\eta$) and a cold Poynting-flux component (defined by magnetization ${\sigma }_0$ at the central engine). We consider the scenarios both without and with sub-photospheric magnetic dissipations. Based on a simplified toy model of jet dynamics, we develop two approaches: a "bottom-up" approach to predict the temperature (for a non-dissipative photosphere) and luminosity of the photosphere emission and its relative brightness for a given pair of $(\eta ,{\sigma }_0)$; and a "top-down" approach to diagnose central engine parameters ($\eta$ and ${\sigma }_0$) based on the observed quasi-thermal photosphere emission properties. We show that a variety of observed GRB prompt emission spectra with different degrees of photosphere thermal emission can be reproduced by varying $\eta$ and ${\sigma }_0$ within the non-dissipative photosphere scenario. In order to reproduce the observed spectra, the outflows of most GRBs need to have a significant $\sigma$, both at the central engine, and at the photosphere. The $\sigma$ value at $10^{15}$ cm from the central engine (a possible non-thermal emission site) is usually also greater than unity, so that internal-collision-induced magnetic reconnection and turbulence (ICMART) may be the mechanism to power the non-thermal emission. We apply our top-down approach to GRB 110721A, and find that the temporal evolution behavior of its blackbody component can be well interpreted with a time-varying $(\eta ,{\sigma }_0)$ at the central engine, instead of invoking a varying engine base size $r_0$ as proposed by previous authors.

41pages, 5 figures, 3 tables, accepted by ApJ

References in corpus (14)

• The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
• Magnetic acceleration of ultra-relativistic jets in gamma-ray burst sources
• Detection of a Thermal Spectral Component in the Prompt Emission of GRB 100724B
• A Comprehensive Analysis of Fermi Gamma-Ray Burst Data. I. Spectral Components and Their Possible Physical Origins of LAT/GBM GRBs
• Prompt GRB emission from gradual energy dissipation
• GRB110721A: An extreme peak energy and signatures of the photosphere
• Quasi-blackbody component and radiative efficiency of the prompt emission of gamma-ray bursts
• A new method of determining the initial size and Lorentz factor of gamma-ray burst fireballs using a thermal emission component
• Hyper-accreting black hole as GRB central engine. I: Baryon loading in GRB jets
• Prompt emission spectra from the photosphere of a GRB
• Gamma Ray Bursts as Electromagnetic Outflows
• Poynting flux dominated jets challenged by their photospheric emission
• Photosphere emission in the X-Ray Flares of Swift Gamma-Ray Bursts and Implications for the Fireball Properties
• Prompt optical emission from residual collisions in GRB outflows

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