Weak Gravitational Fields and Gravitational Waves

Abstract

In this chapter we summarize the most important facts about gravitational waves . We first describe the techniques used for their detection. After discussing their production by moving masses and deriving the relevant formulae from Einstein’s equation ( 2.324), we then estimate their strength for the most relevant astrophysical sources. We discuss the recent first direct detection of gravitational waves emitted from a binary black hole merger by the ground based LIGO interferometers. Next we turn to primordial gravitational waves that could have been produced in the early Universe during inflation or in phase transitions and discuss their detectability. Finally, we present prospects of multi-messenger studies involving gravitational waves, cosmic rays, gamma-rays and neutrinos. A more detailed introduction to gravitational wave physics can be found, for example in Refs. [760–764].