Temporal evolution of prompt GRB polarization

The dominant radiation mechanism that produces the prompt emission in gamma-ray bursts (GRBs) remains a major open question. Spectral information alone has proven insufficient elucidating its nature. Time-resolved linear polarization potential to distinguish between popular mechanisms, e.g., synchrotron from electrons with power-law energy distribution or inverse Compton scattering of soft seed thermal photons, which can yield typical GRB spectrum but produce different levels polarization. Furthermore, it be used learn about outflow's composition (i.e. whether is kinetic-energy-dominated Poynting-flux-dominated) and angular structure. For powerful probe magnetic field geometry. Here we consider thin ultrarelativistic outflow, bulk Lorentz factor $\Gamma(R)=\Gamma_0(R/R_0)^{-m/2}\gg1$, radiates Band-function single (multiple) pulse(s) over range radii, $R_0\leq R\leq R_0+\Delta R$. Pulse profiles evolution at given are presented for coasting ($m=0$) accelerating ($m=-2/3$) spherical shell an off-axis top-hat jet sharp as well smooth edges emissivity. Four configurations considered, such locally ordered coherent scales $\theta_B\gtrsim1/\Gamma$, tangled ($B_\perp$) plane transverse radial direction, ($B_\parallel$) aligned globally toroidal ($B_{\rm tor}$). All distinct (for $B_\perp$ $B_\parallel$) double $B_{\rm tor}$) $90^\circ$ changes position angle.