At the dawn of a new era in astrophysics: Gravitational waves have arrived

Abstract: On 14 September 2016, the Laser Interferometer Gravitational-WaveObservatory (LIGO) detected the first gravitational wave signal everdirectly observed. This observation also represents the first directobservation of a black-hole binary and has opened up a qualitatively newwindow to the universe. We review the key properties of this observationsas well as the second detection GW151226 and briefly review how theextremely weak gravitational wave signal can be extracted throughaccurately source modeling and use of most modern technology. WEfurthermore review the most important classes of gravitational wavesources and discuss some selected examples of the new science we will beable to do with this new observation window.