<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">today!!!<br class=""><div apple-content-edited="true" class="">
<div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">-------------------------------------------</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Francesco Taddia</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Postdoctoral Researcher</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Department of Astronomy</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Stockholm University, Sweden</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy"><a href="mailto:ftadd@astro.su.se" class="">ftadd@astro.su.se</a></font></div></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"><br class="Apple-interchange-newline">
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<br class=""><div style=""><blockquote type="cite" class=""><div class="">On 25 Mar 2015, at 12:01, Francesco Taddia <<a href="mailto:ftadd@astro.su.se" class="">ftadd@astro.su.se</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Dear all,<div class=""><br class=""></div><div class="">tomorrow at 13:00 (usual room) </div><div class="">we will have Damien presenting his paper: <a href="http://arxiv.org/abs/1410.2730" class="">http://arxiv.org/abs/1410.2730</a>.</div><div class="">Here the abstract:</div><div class=""><br class=""></div><div class="">%%%%%%%%%%%%%%%%</div><div class=""><div class="">Poynting flux dominated jets challenged by their photospheric emission. D. Bégué and A. Pe'er<br class="">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<br class="">photospheric emission of Poynting flux dominated outflows, when the dynamics is mediated by magnetic reconnection. We show that thermal three-particle processes, responsible for<br class="">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<br class="">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<br class="">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.<br class="">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<br class="">of magnitude higher than the observed peak energy of most GRBs, which puts strong constraints on the magnetization of these outflows.</div></div><div class="">%%%%%%%%%%%%%%%%</div><div class=""><div apple-content-edited="true" class="">
<div style="letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">-------------------------------------------</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Francesco Taddia</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Postdoctoral Researcher</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Department of Astronomy</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy">Stockholm University, Sweden</font></div><div style="orphans: 2; widows: 2;" class=""><font class="Apple-style-span" face="Noteworthy"><a href="mailto:ftadd@astro.su.se" class="">ftadd@astro.su.se</a></font></div></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"><br class="Apple-interchange-newline">
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