LIGO’s first black hole merger may have been 10 billion years in the making
The LIGO detector has now seen at least two black hole mergers. The second merger it spotted was about what we would expect given a binary system of two massive stars. Both explode, leaving black holes behind that are just a bit more massive than the Sun; these later go on to merge.
But the first merger detected by LIGO was something rather unusual given that both black holes were around 30 times the Sun's mass. So far, we have not observed anything that could produce black holes in that mass range. Now, a new modeling study suggests that mergers with these sorts of masses might be common—but only if stars can collapse directly into a black hole without exploding first. This situation would require some of the Universe's most luminous stars to simply be winking out of existence.
The black holes involved in these mergers almost certainly began their existence as binary star systems. So in the new study, the authors performed a massive number of simulations of these systems using a modeling package called StarTrack. The simulations took into account the different amount of heavy elements present at different times in the Universe's existence—there are 32 different levels of heavy elements, and the team ran 20 million simulations at each of them. The simulations also took into account various models of the collapse of massive stars, as well as whether the process generated an asymmetrical force that could kick the resulting black hole into an energetic orbit.
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Source: Scientific Method – Ars Technica http://ift.tt/28N6uL0
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