We showcase the Gravitational-Wave Transient Catalog 4.0, a record of cosmic mergers detected between 2015 and 2024 by the LIGO, Virgo, and KAGRA gravitational wave observatories. Each panel is a time and frequency signature of an individual event the merger of two black holes, neutron stars, or one of each, somewhere out in the cosmos.

As these dense objects spiral into one another, they send out ripples in the fabric of spacetime called gravitational waves. The rising swoosh in each panel shows how the gravitational wave signal of a merger grows louder and higher-pitched right before the final collision, known as a chirp.

The events are arranged by observing runs. Each run is highlighted with its own color palette, showing how the catalog has grown in the past decade. In the earliest run (O1), only three signals appeared, while O2 observed eight events, and O3 observed 79 events. We present for the first time the first part of the fourth observing run (O4a), which includes 128 new events. Thus, the Gravitational-Wave Transient Catalog 4.0 contains 218 events detected over the last decade.[Credit: Ryan Nowicki / Bill Smith / Karan Jani]