Astroparticle Physics

29916 Glossary“A good notation has a subtlety and suggestiveness,which at times makes it almostseem like a live teacher.”Bertrand RussellAThe total luminosity emitted from an astrophysical object.Lowest possible temperature, 0 Kelvin, at which all motion comesto rest except for quantum effects (0 Kelvin =−273.15 ◦ Celsius).Percentage of an element occurring on Earth, in the solar system,or in primary cosmic rays in a stable isotopic form.It describes the acceleration of the universe in its dependence on theenergy density and negative pressure (i.e., due to the cosmologicalconstant).A measurement for the change of the expansion rate with time. Foran increased expansion rate the acceleration parameter is positive.It was generally expected that the present expansion rate is reducedby the attractive gravitation (negative acceleration parameter = deceleration).The most recent measurements of distant supernovae,however, contradict this expectation by finding an accelerated expansion.A machine used to accelerate charged particles to high speeds.There are, of course, also cosmic accelerators.Accumulation of dust and gas into a disk, normally rotating arounda compact object.After decoupling of matter from radiation the pattern of acousticoscillations of the primordial baryon fluid became frozen as structuresin the power spectrum of the CMB.Galaxy with a bright central region, an active galactic nucleus.Seyfert galaxies, quasars, and blazars are active galaxies, whichare presumably powered by a black hole.In the Big Bang model the inverse of the Hubble constant is identifiedwith the age of the universe. The present estimate of the ageof the universe is about 14 billion years.absolute brightnessabsolute zeroabundanceacceleration equationacceleration parameteracceleratoraccretion diskacoustic peaksactive galaxyage of the universe