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Close Binary Black Hole Systems Methods of Merger

Presentation #338.03 in the session “Compact Object Binaries”.

Published onJan 11, 2021
Close Binary Black Hole Systems Methods of Merger

This research is the culmination of a project by a 10th grade Astronomy Class. Black hole mergers can potentially be formed by the merging of a close-binary system of tidally-locked chemically homogeneous helium stars. According to popular theory, very large helium stars (helium stars with masses over 63 Msun) are capable of exploding without being gravitationally-bound and therefore leave nothing behind, so the near-homogeneous helium stars in question must be well below this mass in order to merge and produce gravitational waves. Until recently, all detected gravitational wave events detected by LIGO were modeled to have formed from mergers of either binary black holes or neutron stars of less than this 63Msun limit or from the collapse of supermassive stars of 200Msun into black holes with masses of about 120Msun. Thus a mass gap for black hole formation between 63 and 120 times the solar mass, the ‘pair instability gap’ has been theorized. However, a recent detection by LIGO involved the merger of two stars, one of which is apparently within the pair instability mass gap. In addition, LIGO data suggests that the stars were neither aligned or spinning in the same direction, a characteristic that seems to refute black hole merger theory that requires aligned binary black hole systems. Perhaps there are more than one mechanism that leads to black hole mergers, an idea that many modern scientists resist. Our ongoing research promises to follow and summarize LIGO discoveries and subsequent adjustments in theory relating to the generation of gravitation waves.

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