Goldilocks black holes are rare, new gravitational wave study suggests

May 24 (UPI) -- LIGO is designed specifically to look for the collisions of medium-sized black holes. While it hasn't found any, the search and related analysis has allowed astronomers to more accurately predict the abundance of so-called Goldilocks black holes.

Their work suggests Goldilocks black holes are exceptionally rare.

LIGO has detected black hole collisions. The first gravitational wave to be detected by LIGO was generated by the collision of two small black holes -- black holes measuring just 10 solar masses.

Black holes are either small are supermassive, with masses a million times greater than the mass of the sun. Direct evidence of black holes measuring in between the two extremes is nonexistent. Indirect evidence is scant.

The latest survey suggests Goldilocks black holes are elusive because there are so few. The survey looked for medium-sized black holes among 100 million Milky Way-sized galaxies across a timeline of 5 billion years.

"Clearly they are much, much rarer than low-mass black holes, three collisions of which LIGO has detected so far," Karan Jani, a former Georgia Tech doctoral physics student, said in a news release.

Researchers at the Georgia Institute of Technology collaborated with dozens of scientists from all over the world to complete the survey.