“The interesting thing is: we have no idea!” says Pieter van Dokkum, Sol Goldman Professor of Astronomy at Yale University, who wrote in an email to The Daily Galaxy about why ultra-diffuse galaxy DF2 contains no dark matter. “The existence of this galaxy shows that there is another pathway to creating galaxies than our standard picture, but what that might be is anyone’s guess.”
“I spent an hour just staring at this image,” lead researcher, astronomer Pieter van Dokkum of Yale University says as he recalls first seeing the Hubble image of NGC 1052-DF2, a galaxy completely void of dark matter. “This thing is astonishing, a gigantic blob so sparse that you see the galaxies behind it. It is literally a see-through galaxy. It’s so rare, particularly these days after so many years of Hubble, that you get an image of something and you say, ‘I’ve never seen that before.”
“It really is quite uncomfortable. It shouldn’t exist; it shouldn’t be real,” Marla Geha, an astronomer at Yale University , said in 2018 of a small, strange galaxy a small galaxy that seems to contain none of the invisible stuff known as dark matter. “Yet if you look at the data, that’s the conclusion you’re drawn to.” Astronomers have long noticed an invisible elephant in the room — so-called dark matter, which seems heavier than all the visible stars, gas and dust in the cosmos by a ratio of 6-to-1.