An anonymous reader writes: Already, the new gravitational-wave data has shaken up the field of astrophysics. In response, three dozen experts spent two weeks in August sorting through the implications at the Kavli Institute for Theoretical Physics (KITP) in Santa Barbara.
Jump-starting the discussions, de Mink, an assistant professor of astrophysics at the University of Amsterdam, explained that of the two — and possibly more — black-hole mergers that LIGO has detected so far, the first and mightiest event, labeled GW150914, presented the biggest puzzle. LIGO was expected to spot pairs of black holes weighing in the neighborhood of 10 times the mass of the sun, but these packed roughly 30 solar masses apiece. “They are there — massive black holes, much more massive than we thought they were,” de Mink said to the room. “So, how did they form?”
The mystery, she explained, is twofold: How did the black holes get so massive, considering that stars, some of which collapse to form black holes, typically blow off most of their mass before they die, and how did they get so close to each other — close enough to merge within the lifetime of the universe? “These are two things that are sort of mutually exclusive,” de Mink said. A pair of stars that are born huge and close together will normally mingle and then merge before ever collapsing into black holes, failing to kick up detectable gravitational waves.