Galaxy's 2 Million MPH Crash Creates Cosmic 'Sonic Boom'

Published in Monthly Notices of the Royal Astronomical Society | Estimated reading time: 4 minutes

Using the newly commissioned 20-million Euro WEAVE telescope in La Palma, Spain, scientists observed this celestial crash occurring in Stephan’s Quintet, a group of five galaxies that has fascinated astronomers since its discovery in 1877. The intruding galaxy, designated NGC 7318b, is plowing through a complex field of galactic debris, reawakening ancient cosmic turmoil.

Dr. Marina Arnaudova of the University of Hertfordshire, who led the research, describes the collision as a “galactic crossroad” where past galaxy interactions have left their mark. “The shock created by this collision is so powerful it can strip electrons from atoms, leaving behind a glowing trail of charged gas that we can observe with our instruments.”

The research team, comprising over 60 astronomers, made a surprising discovery about the nature of these cosmic shock waves. When the supersonic disturbance encounters pockets of cold gas, it creates intense, glowing trails. However, its behavior changes dramatically when passing through hotter regions, where it compresses the gas and generates distinctive radio waves.

This dual nature of the shock front, previously unknown to astronomers, was revealed through the combined power of multiple cutting-edge instruments, including the Low Frequency Array (LOFAR), the Very Large Array (VLA), and the James Webb Space Telescope (JWST).