The Missing Link: Where Are Medium-Size Black Holes?
By Charles Q. Choi, Live Science Contributor | June 24, 2017 08:40am ET
For decades, while astronomers have detected black holes equal in mass either to a few suns or millions of suns, the missing-link black holes in between have eluded discovery. Now, a new study suggests such intermediate-mass black holes may not exist in the modern-day universe because of the rate at which black holes grow.
Scientists think stellar-mass black holes — up to a few times the sun's mass — form when giant stars die and collapse in on themselves. Over the years, astronomers have detected a number of stellar-mass black holes in the nearby universe, and in 2010, researchers detected the first such black hole outside the local cluster of nearby galaxies known as the Local Group.
https://www.livescience.com/55419-missing-link-intermediate-mass-black-holes.html
