My research interests cover a wide variety of subjects in high-energy astrophysics and space physics, including: Gamma-ray bursts (the strongest and brightest explosions in the Universe), relativistic shock waves, magnetic field generation, radiation physics, observational aspects. Astrobiology: how life on Earth has been (and will be) affected by cosmogenic factors, such as gamma-ray bursts, supernovae, energetic solar flares, etc. Accretion physics: the dynamics of the gas infall onto strongly gravitating objects, signatures of black holes and neutron stars in the accretion spectra. Colsmology: transport phenomena (e.g. thermal conduction) in galaxy clusters, transport in irregular and chaotic magnetic fields, origin of magnetic fields in the Universe. Solar and stellar wind physics: structure of termination shocks, charge-exchange x-rays from shocks, nonlinear waves in the solar wind.