engadget: In this case, the culprit was likely a recent merger of two black holes made soon after the dawn of the universe. by David Lumb
'"We play God," lead study author Chris Belczynski, an astrophysicist at Warsaw University, told The Verge. "We have a model of the entire Universe in our computer. We populate the computer with stars from the beginning, from the Big Bang, and you let them go ahead, evolve, produce black holes, etc."
'Since Synthetic Universe's simulation also includes a mock-LIGO to chronologically sync when we detected the waves, the model is also predictive, the study argues. If correct, we should see LIGO pick up to 60 detections when it starts "listening" for the waves again in fall. At its peak sensitivity, it could hear up to 1,000 detections annually.
'Belczynski's speculation specifies the size of black hole mergers that the LIGO should be able to detect from gravitational waves, a combined mass between 20 and 80 times the mass of our sun. That large size indicates that they're likely from just after the Big Bang, when stars had lower metal content and formed proportionately larger black holes.'