Early models of cosmological GRBs predicted the observed spectrum to be nearly blackbody. Observations were at odds with this prediction, and different theoretical models assuming optically thin emission have been put forward. However, models of such non thermal emission appear to be inconsistent with observations of steep spectra in early phases of many GRBs. Instead models involving photospheric emission producing modified blackbody spectra explain such observed spectra quite naturally.

We plan to discuss physical aspects of photospheric emission in ultrarelativistic sources as well as observational issues related to the detection of such a photospheric component in GRBs. Special attention is expected to be given to sub-photospheric dissipation mechanisms, geometric and dynamical effects, jet content, and additional components in the observed spectrum.

Final program:

14:00-14:05 Felix Ryde and Gregory Vereshchagin Opening
14:05-14:30 Asaf Pe'er Theory of photospheric emission in GRBs
14:30-14:55 Dimitrios Giannios Photospheric emission in the magnetic outflow models in GRBs
14:55-15:10 Amir Levinson Observational signatures of sub-photospheric shocks in GRBs
15:10-15:25 Gregory Vereshchagin Physics of non-dissipative ultrarelativistic photospheres
15:25-15:40 Romain Hascoet The nature of GRB relativistic outflows: temporal and spectral signatures
15:40-15:50 Christoffer Lundman A theory of photospheric emission from collimated outflows
15:40-16:00 Ivan Siutsou Photon thick and photon thin relativistic outflows and GRBs
16:00-16:30 Coffe break
16:30-16:45 Giacomo Vianello Fermi GRB spectra and the crisis of the Band model
16:45-17:00 Felix Ryde What did we learn from GB090902B and GRB110721A?
17:00-17:15 Sinead McGlynn Photospheric Emission in Fermi Gamma Ray Burst Monitor GRBs
17:15-17:30 Sylvain Guiriec Multi-Component Spectral Analysis of Fermi GRBs: a Step Forward in the Understanding of the Prompt Emission
Numerical Simulations
17:30-17:45 Indrek Vurm Thermalization in GRB jets and peak energies of photospheric spectra
17:45-18:00 Akira Mizuta Photospheric thermal radiation from GRB jets
18:00-18:15 Alexei Aksenov Radiative transfer near the photosphere of mildly and ultrarelativistic outflows
18:15-18:30 Katsuaki Asano Photospheric Emission in time-dependent simulations
18:30-18:45 Luca Izzo The SN-GRB connection in GRB 090618 and GRB 970828
18:45-18:55 Marco Muccino GRB 090227B: the first example of a genuine short GRB
18:55-19:15 Felix Ryde and Gregory Vereshchagin Concluding remarks
Poster session
  Damien Bégué Monte Carlo simulations of the photospheric emission in GRBs