Astroparticle Physics

16 Glossary 315The interaction of particles due to their mass or energy. Also particleswithout rest mass are subject to gravitational interactions ifthey have energy, since energy corresponds to mass according tom = E/c 2 .A large mass causes a strong curvature of space thereby deflectingthe light of a distant radiation source. Depending on the relativeposition of source, deflector, and observer, multiple images, arcs,or rings are produced as images of the source.Increase of the wavelength of electromagnetic radiation in thecourse of emission against a gravitational field.Supersymmetric partner of the graviton.Massless boson with spin 2¯h mediating the interaction betweenmasses.Attractive force between two bodies caused by their mass. Thegravitation between two elementary particles is negligibly smalldue to their low masses.In the same way as an accelerated electrical charge emits electromagneticradiation (photons), accelerated masses emit gravitationalwaves. The quantum of the gravity wave is called the graviton.A 100 Mpc structure seen in the distribution of galaxies.Threshold energy of energetic protons for pion production off photonsof the cosmic background radiation via the ∆ resonance.Unified theory of strong, electromagnetic, and weak interactions.The very early universe when the strong, weak, and electromagneticforces were unified and of equal importance.Energy scale at which strong and electroweak interactions mergeinto one common force, E ≈ 10 16 GeV.A charged particle moving in a magnetic field will orbit around themagnetic field lines. The radius of this orbit is called the gyroradiusor sometimes also the Lamor radius.A particle consisting of strongly interacting constituents (quarksor gluons). Mesons and baryons are hadrons. All these particlesparticipate in strong interactions.gravitational interactiongravitational lensgravitational redshiftgravitinogravitongravitygravity wavesGreat WallGreisen–Zatsepin–Kuzmin cutoff(GZK)GUT (Grand Unified Theory)GUT epochGUT scalegyroradiusHhadron