The old science thread seems to have gotten locked, not sure what the rules are but I thought we could try again.
Pretty neat preprint out from The
LOFAR Sky Survey. They use low frequency radiation (<100MHz) to map the sky.Most of the paper deals with the technical details, they have to use multiple telescopes separated by 1000s of miles to eliminate noise (the Earth's atmosphere interferes a ton with radiation in that frequency range), but the end result is a nice picture of just
supermassive black holes in distant galaxies.
That's about 20k SMBHs in about 5% of the sky. It was widely believed before that SMBHs holes are very common, since they've been found in the galactic centers close enough to resolve, but nice to see more confirmation as LOFAR is equipped to see very high energy point sources, which is dominated by accretion disks of SMBHS.
I find this really interesting mostly because it's still a mystery how these things even exist. Hopefully we will get a better picture of how SMBHs form in the first place, because it's likely a completely different process than what forms stellar black holes.