Astronomers Find 19 More Galaxies Missing Their Dark Matter

Iwastheone shares a report from Astronomy.com: Astronomers have discovered 19 more galaxies missing their dark matter. Instead of dark matter, these strange galaxies are mainly filled with regular matter, like the protons, neutrons, and electrons that make up everything we're familiar with. The new find, published November 26 in Nature Astronomy, bolsters the controversial recent discovery of two other galaxies without dark matter. The mysterious substance accounts for most matter in the universe, and it's thought to be the primary component of all galaxies -- as well as the main driver of galaxy formation in the first place. So, finding so many galaxies without the exotic matter suggests astronomers are missing something major about how galaxies form and evolve. "This result is very hard to explain using the standard galaxy formation model," said lead author Qi Guo of the Chinese Academy of Science in a press release, "and thus encourages people to revisit the nature of dark matter." The latest batch of galaxies missing dark matter was discovered when Guo and her team explored the nature of 324 dwarf galaxies using data from the Arecibo Observatory in Puerto Rico and the Sloan Digital Sky Survey. With this data, they followed in the footsteps of Rubin and Ford, studying how fast hydrogen gas rotates around each galaxy. They also calculated how much normal matter -- in the form of both gas and stars -- they contained. After crunching the numbers, Guo and her colleagues determined that, of the 324 dwarf galaxies they investigated, 19 of them contain enough visible matter to solely explain the motions of the galaxies' hydrogen. In other words, a lot of dark matter seems to be missing from these galaxies.Read more of this story at Slashdot.
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