New Paper: Synchrotron emission in GRBs observed by Fermi: limitations, the role of the photosphere

Former PhD student Shabnam Iyyani, who is now a post doc at TIFR in Mumbai, got her most recent paper accepted. The paper presents a study of a sample of Fermi GRB spectra which are modelled by using synchrotron emission in addition to photospheric emission. She investigated the properties of the jet and the physical requirements set by the observations and finds, e.g.,  a robust results that the bulk Lorentz factor decreases monotonously over the pulses and lies between 1000 and 100,  a behaviour that challenges internal shocks. The paper discussed in detail the synchrotron scenario and argue  that it presents several limitations that need to be addressed and discusses alternative interpretations such as subphotospheric dissipation models. Read the paper in  ArXiv .