June 29, 2023
The universe has spent billions of years making things that shine. On your birthday, we celebrate one of its quieter masterpieces.
A Message from the Gravitational Universe
Birthday · June 29, 2023
A little universe, just for you
Your date.
Ready to give.
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APOD published June 29, 2023. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
Monitoring 68 pulsars with very large radio telescopes, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has uncovered evidence for the gravitational wave (GW) background by carefully measuring slight shifts in the arrival times of pulses. These shifts are correlated between different pulsars in a way that indicates that they are caused by GWs. This GW background is likely due to hundreds of thousands or even millions of supermassive black hole binaries. Teams in Europe, Asia and Australia have also independently reported their results today. Previously, the LIGO and Virgo detectors have detected higher-frequency GWs from the merging of individual pairs of massive orbiting objects, such as stellar-mass black holes. The featured illustration highlights this spacetime-shaking result by depicting two orbiting supermassive black holes and several of the pulsars that would appear to have slight timing shifts. The imprint these GWs make on spacetime itself is illustrated by a distorted grid. Open Science: Browse 3,000+ codes in the Astrophysics Source Code Library