Lightcurves and spectral features of X-ray afterglows of gamma-ray bursts Original Research Article

We consider the temporal behaviour and spectra of early X-ray afterglows of Gamma-Ray Bursts (GRBs) and identify peculiarities imprinted by dynamcal processes in GRB shocks. It is shown that the bolometric lightcurve may deviate from monotonous decline when the late-time energy injection takes place via a secondary shock. The latter is formed by a neutron component of outflow, which is present in any stellar-type GRB model and carry as much energy as the proton component. Kinetic processes in the emitting region give rise to a break in the spectrum of X-ray emission of synchrotron origin related to a break in the electron distribution function, which appears due to transition from synchrotron cooling (for the most energetic electrons) to Compton cooling (for less energetic ones). The new generation of X-ray missions with greatly enhanced sensitivity offers a breakthrough in understanding of dynamics of early GRB afterglows.