Gravitational Wave Astronomy: Detection Methods and Astrophysical Implications

Abstract

The direct detection of gravitational waves in September 2015 by the Advanced LIGO observatories opened a new observational window on the universe. In less than a decade the field has transitioned from a single detection to a catalogue of nearly a hundred compact-binary coalescences, together with the multi-messenger observation of a binary neutron-star merger in 2017 that simultaneously produced gravitational waves, electromagnetic emission, and kilonova signatures. This paper reviews the theoretical background of gravitational waves, the principles and performance of laser-interferometric detectors, the catalogue of significant detections, and the astrophysical implications for compact-object populations, tests of general relativity, cosmology, and the origin of heavy elements. Future detector generations LIGO Voyager, the Einstein Telescope, Cosmic Explorer, and the space-based LISA are expected to extend reach to high redshifts and to lower frequencies inaccessible to ground-based instruments.