Talk detail

Participant	Vereshchagin, Gregory
Institution	ICRANet - p.le della Repubblica, 10 - Pescara - - Italy

Session	GRB1	Accepted	Yes	Order	4	Time	15:10 - 15:25
Talk	Oral abstract	Title	Physics of non-dissipative ultrarelativistic photospheres
Co-authors
Abstract	Relativistic astrophysical sources have some interesting features which do not find their counterparts among nonrelativistic objects. In static spherically symmetric objects the form of the photosphere is clearly spherical and their observed spectrum has a Planck shape. When relativistically moving objects are considered, geometry of the photosphere becomes nontrivial and knowing its dynamics is essential for understanding their spectra. The observed spectrum of photospheric emission may strongly deviate from the Planckian one. I will discuss several physical effects leading to deviations of photospheric spectrum from the Planckian shape, in particular the diffusion in energy, the diffusion in space, angular and radial distributions of the last scattering which all contribute to such deviations. Implications for GRB photospheres will be outlined.