Speaker
Description
Thanks to the Fermi Large Area Telescope (LAT), novae have been established as a new class of particle accelerators and gamma-ray emitters, with 9 objects detected as transient GeV sources so far. A possible origin for this non-thermal emission is internal shocks in the nova ejecta, resulting from the interaction of a fast wind radiatively-driven by nuclear burning on the white dwarf with material ejected in the initial runaway stage of the outburst.
We present a model for the dynamics of such internal shocks and for the associated diffusive shock acceleration and high-energy emission. Non-thermal proton and electron spectra are calculated by solving a time-dependent transport equation for particle injection, acceleration, losses, and escape from the shock region. Predicted spectra and lightcurves are fitted to observations of the first 6 novae detected by the LAT to derive the properties of the nova outbursts. From these results, we discuss the potential of gamma-rays for probing the mechanism of mass ejection in novae in conjunction with diagnostics of the thermal emission.
