04/21/2016: Hunt Continues for Gravitational Waves from Black Hole Megamergers

The sound of merging supermassive black holes ^[1] does not saturate the universe.

For the past decade, scientists with the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration have been listening for a constant “hum” of low-frequency gravitational waves ^[2].

Theoretical work suggests that this hum — generated by collisions involving supermassive black holes, which contain millions or billions of times more mass than the sun — should be detectable at Earth. NANOGrav hasn’t heard the hum yet, a new study reveals, but this lack of detection is an interesting result in its own right, revealing new details of how galaxies might evolve and merge, team members said. [The Search for Gravitational Waves in Pictures ^[3]]