Astroparticle Physics

16 Glossary 321Distant galaxies with a bright active galactic nucleus emitting inthe blue and UV range. The Markarian galaxies are also sources of≥ TeV gamma rays.Rest mass; the rest mass m 0 of a particle is that mass, which oneobtains, if the energy of an isolated free particle in the state ofrest is divided by the square of the velocity of light. When particlephysicists use the name mass, they always refer to the rest mass ofa particle.The sum (A) of the number of neutrons (N) and protons (Z) inanucleus.An asymmetry created by some, so far unknown baryon- and lepton-number-violatingprocess in the early universe (see Sakharovconditions).Flavour oscillations which can be amplified by matter effects in aresonance-like fashion; e.g., suppression of solar neutrinos in ν e e −interactions in the Sun.Moment when the energy density of radiation dropped below thatof matter at around 50 000 years after the Big Bang.A hadron consisting of a quark and an antiquark.A small dark object in the line of sight to a bright background starcan give rise to a brightness excursion of the background star dueto a bending of the light rays by the dark body.Extremely small (≈ µg) black holes could have been formed in theearly universe. These primordial black holes are not final states ofcollapsing or evaporating stars.Mass or energy in cosmology which must be present because ofits gravitational force it exerts on other matter. The missing massdoes not emit detectable electromagnetic radiation (see dark matter).Missing mass is also encountered in relativistic kinematics,where in many experiments, in which total energy is fully constrainedby the center-of-mass energy, the mass, energy, and momentumof particles escaping from the detector without interaction(like neutrinos or SUSY particles), can be reconstructed due to thedetection of all other particles.See Friedmann–Lemaître universes.All grand unified theories predict large numbers of massive magneticmonopoles in contrast to observation. Inflation during the eraof monopole production would have diluted the monopole densityto a negligible level, thereby solving the problem.Markarian galaxiesmassmass numbermatter–antimatter asymmetrymatter oscillationmatter–radiation equalitymesonmicrolensingmini black holesmissing massmodels of the universemonopole problem