Black Hole Breakthrough at LIGO/VIRGO?

During the first two runs (O1 and O2, 2015–2017) of the LIGO gravitational wave detectors, researchers observed 2 merger objects that had masses below the standard core-collapse black hole mass range. Both were believed to be neutron stars that produced the expected pyrotechnics.

After upgrading the system and increasing its sensitivity, O3 began in April 2019 and has run for about 6 months. During that time 11 merger objects with masses below the standard core collapse black hole mass range have been detected. The rate of detecting these low mass merger objects has noticeably increased over those 6 months. A very interesting, and possibly a key diagnostic clue, is the fact that little in the way of electromagnetic fireworks has been associated with these new low mass events.

If some of these low mass merger objects are black holes, rather than all being neutron stars, then the case for primordial black holes as the premier dark matter candidate has been significantly strengthened. This would potentially represent a game-changing development in the decades-long efforts to solve the dark matter enigma.

What is needed now is more information on the masses of the low mass objects. Alas, the LIGO/VIRGO collaboration has not been forthcoming with preliminary estimates and uncertainty ranges for these highly relevant masses. The word is that they hope to have at least some of this information published by next Spring.

We can only hope that such an important mystery can be addressed as soon as the data becomes available.