X-raying the sky - astronomy

“In the past 60 years X-ray astronomy has established itself as a stable aspect of ‘multi-wavelength astronomy’, which extends from long-wave radio to hard gamma radiation. Currently, strong new impulses are coming from recent gravitational wave astronomy, which on several occasions since 2016 has detected signals deriving from the union of two massive black holes.”

Joachim Trümper, astrophysicist, Max Plack Institute for Extraterrestrial Physics, 2020