Artwork shows the merger of two black holes, which gives off a burst of gravitational waves. (SXS Graphic)
Two detections of gravitational waves, separated by a mere 21 minutes, set off a flurry of excitement among astronomers today.
Was it a binary black-hole merger? A double observation of a single black-hole merger, created by gravitational lensing effects? A glitch affecting the analytical systems at the world’s gravitational-wave detectors? Or merely a coincidence of cosmic proportions?
“This is a genuine ‘Uh, wait, what?’ We’ve never seen that before…….’ moment in gravitational wave astronomy,” Robert Rutledge, a physicist at McGill University, tweeted today. “If you’d like to see how double-checks and confirmations and conclusions occur – pay attention, in real time. Happening now.”
As the hours ticked by, the most intriguing likelihood – that the ripples in spacetime were warped and refocused by a powerful gravitational field in accordance with general relativity – appeared to become much less likely.
A closer look at the data for the events, known as S190828j and S190828l, suggested that they did not emanate from the same location on the sky, as was earlier thought.
“The sky localizations are similar, but distinct,” Northwestern University Christopher Berry, a ...