Gamma-Ray Bursts: Super-Explosions in the Universe and Related High-Energy Phenomena

The recent progress in studies of gamma-ray bursts, their afterglows, and host galaxies is discussed. The emphasis is given to high-energy phenomena associated with gamma-ray burst explosions: high-energy cosmic rays, neutrinos, gravitational waves. We also show how the relativistic fireball model for GRBs can be used to constrain modern theories of large and infinite extra-dimensions. In particular, in the frame of 5D gravity with the Standard Model localized on 3D brane (Dvali et al. 2000), the very existence of relativistic fireballs of $\sim 10^{53}$ ergs puts the lower bound on the quantum gravity scale $\sim 0.1$ eV.