“What’s really exciting is what comes next. I think we’re opening a window on the universe — a window of gravitational wave astronomy.” -Dave Reitze
On September 14, 2015, LIGO directly detected gravitational waves for the first time, from the inspiral-and-merger of two quite massive black holes. Despite the fact that no electromagnetic radiation signal was expected, the Fermi GBM instrument measured a high-energy X-ray event just 0.4 seconds after LIGO’s 200 millisecond detection occurred. According to NASA scientists working on the Fermi mission, there was just a 0.2% chance of a false positive.
In a new paper out today, however, a reanalysis using a superior statistical method shows that the 0.2% chance is, in fact, true, and that LIGO’s black holes didn’t have an electromagnetic counterpart after all. This new statistical technique will be incredibly useful down the road for discriminating between robust astrophysical signals and spikes in the noise that have hitherto been a source of incredible confusion.