📚 Evidence of 'Modified Gravity' In 150 Galaxies Strengthens Dark Matter Alternative

A team of astronomers has discovered evidence in over 150 galaxies for a long-standing alternative model of "modified gravity." New Atlas reports: [R]esearchers on the new study say they've observed the [external field effect] (EFE) in action in 153 different galaxies. The team was studying the rotation curve of the galaxies, which plots the orbital speed of stars and gas against their distance from the center of the galaxy. The researchers discovered that galaxies in strong external fields slowed down much more frequently than galaxies in weaker external fields did. That's a prediction made only by [Modified Newtonian dynamics] MOND, and the discovery surprised even the astronomers themselves. "The external field effect on rotation curves is expected to be very tiny," says Federico Lelli, co-author of the study. "We spent months checking various systematics. In the end, it became clear we had a real, solid detection." It's an intriguing result, and it may lend some weight to the MOND hypothesis for further study. But it's important to keep in mind that so far the bulk of the evidence still points towards dark matter, and it'll take much more work to topple that hypothesis entirely. The research was published in the Astrophysical Journal.

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