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Class of Large But Very Dim Galaxies Discovered (nature.com)
schwit1 writes from a report via Nature: Astronomers have now detected and measured a new class of large but very dim galaxy that previously was not expected to exist. Nature reports: "'[Ultradiffuse]' galaxies came to attention only last year, after Pieter van Dokkum of Yale University in New Haven, Connecticut, and Roberto Abraham of the University of Toronto in Canada built an array of sensitive telephoto lenses named Dragonfly. The astronomers and their colleagues observed the Coma galaxy cluster 101 megaparsecs (330 million light years) away and detected 47 faint smudges. 'They can't be real,' van Dokkum recalls thinking when he first saw the galaxies on his laptop computer. But their distribution in space matched that of the cluster's other galaxies, indicating that they were true members. Since then, hundreds more of these galaxies have turned up in the Coma cluster and elsewhere. Ultradiffuse galaxies are large like the Milky Way -- which is much bigger than most -- but they glow as dimly as mere dwarf galaxies. It's as though a city as big as London emitted as little light as Kalamazoo, Michigan." More significantly, they have now found that these dim galaxies can be as big and as massive as the biggest bright galaxies, suggesting that there are a lot more stars and mass hidden out there and unseen than anyone had previously predicted.
Turns out the more mass you were trying to account for happens to just be more mass you didn't see.
I was under impression that dark matter was mainly to explain how galaxies work on 'small scale' (galaxy and galaxy cluster), rather than on entire universe scale. Having dim galaxies out there won't explain why other galaxies are spinning too fast and not falling apart.
It would still give off the same total energy, shifted into the IR...or much lower. I wonder if they detected longer wavelengths.
I also wonder if thjs impacts the estimate for total number of galaxies at 100 billion.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.