Today Selma de Mink (Harvard) gave a great and energizing Astrophysics Seminar at NYU. She talked about many things related to the extremely massive-star progenitors of the estremely massive black holes being observed in merger by LIGO. One assumption of her talk, which is retrospectively obvious but was great, is that the vast majority of LIGO events should be first-generation mergers. A second merger is very unlikely, dynamically. But that wasn't her point: Her point was that the masses that LIGO sees will constrain how very massive stars evolve. In particular, she showed that there is a strong prediction of a mass gap: There can't be black holes formed by stellar evolution in the mass range 45 to 150 solar masses. The physics is all about pair-instability supernovae from very low-metallicity stars. But the details of this black-hole mass gap depend on some nuclear reaction rates, so she concludes that LIGO will make nucleosynthetic measurements! The LIGO data probably already do. It's a new world!
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