Quasars

Did you know?

"If quasars were common beyond redshift 7.5, then astronomers would have found several more by now. But their spatial density --the numbers of quasars in a given volume of space--appears to be very low, only about one quasar per cubic gigaparsec, where a gigaparsec is 3.26 billion light years. "You have to survey huge areas of the sky to find these objects just because they are intrinsically so rare in the universe."

Astronomy Magazine April  2022 "How to Grow a Giant Black Hole" pp. 18-19