[Okc-wp4] Reminder: EO meeting

[Francesco Taddia]

today!!!
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Francesco Taddia
Postdoctoral Researcher
Department of Astronomy
Stockholm University, Sweden
ftadd at astro.su.se <mailto:ftadd at astro.su.se>







> On 25 Mar 2015, at 12:01, Francesco Taddia <ftadd at astro.su.se> wrote:
> 
> Dear all,
> 
> tomorrow at 13:00 (usual room) 
> we will have Damien presenting his paper: http://arxiv.org/abs/1410.2730 <http://arxiv.org/abs/1410.2730>.
> Here the abstract:
> 
> %%%%%%%%%%%%%%%%
> Poynting flux dominated jets challenged by their photospheric emission.   D. Bégué and A. Pe'er
> One of the key open question in the study of jets in general, and jets in gamma-ray bursts (GRBs) in particular, is the magnetization of the outflow. Here we consider the
> photospheric emission of Poynting flux dominated outflows, when the dynamics is mediated by magnetic reconnection. We show that thermal three-particle processes, responsible for
> the thermalization of the plasma, become inefficient at a radius r_sup \sim 10^9.5 cm, far below the photosphere, at \sim 10^11.5 cm. Conservation of the total photon number
> above r_sup combined with Compton scattering below the photosphere enforces kinetic equilibrium between electrons and photons. This, in turn, leads to an increase in the
> observed photon temperature, which reaches >8 MeV (observed energy) when decoupling the plasma at the photosphere. This result is weakly dependent on the free model parameters.
> We show that in this case, the expected thermal luminosity is a few \% of the total luminosity, and could therefore be detected. The predicted peak energy is more than an order
> of magnitude higher than the observed peak energy of most GRBs, which puts strong constraints on the magnetization of these outflows.
> %%%%%%%%%%%%%%%%
> -------------------------------------------
> Francesco Taddia
> Postdoctoral Researcher
> Department of Astronomy
> Stockholm University, Sweden
> ftadd at astro.su.se <mailto:ftadd at astro.su.se>
> 
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