Magnetic Compton resonant scattering as a production mechanism ofnarrow-band gamma-rays from multi-PW lasers irradiating solid targets

Magnetic Compton resonant scattering of soft photons by relativistic electrons in superstrong magnetic fields has been widely studied as the source of multi-MeV gamma-rays from pulsars and magnetars. Here we propose that under favorable conditions, similiar processes may occur in multi-PW laser focal spots on solid targets, leading to the copious production of narrow-band gamma-rays. Multi-PW laser-created magnetic fields can be Lorentz-boosted in the electron rest frame to a fraction of teragauss or higher, similar to the surface field of neutron stars. In this case Compton scattering is dominated by narrow resonances at the electron gyrofrequency and its harmonics, with peak cross sections many orders of magnitude larger than the Thomson cross-section. Soft photons with the right angle and energy can be efficiently upscattered via the narrow resonance, producing narrow-band gamma rays emitted along the forward direction of the electron momentum. We will present detailed numerical simulations of the gamma-ray output under various laser and target conditions, and discuss potential applications of narrow-band gamma-rays.