The stars and gas of the strange galaxy known as AGC 114905 were mapped out by Astronomers.
Three years ago, Filippo Fraternali and his colleagues spotted a half dozen mysteriously diffuse galaxies, which looked like cities of stars and gas. They didn't seem to be enshrouded in huge amounts of dark matter, which would normally hold those stellar metropolises together with their gravity. The Very Large Array in New Mexico was pointed at by the scientists because they wanted to zoom in on a small galaxy about 250,000 light-years away.
After gathering 40 hours of data, they mapped out the stars and gas and confirmed what the earlier snapshots had suggested. It could pose a challenge for scientists to view dark matter in a different way if the team or their competitors find other such galaxies. The findings were published in December in the Monthly Notices of the Royal Astronomical Society.
Scientists think of dark matter as the hidden skeleton of the universe, because of the large clumps of invisible particles which host large and small galaxies. Fraternali is not the first to see an exception to that rule. A few years ago, an astronomer at Yale, and his colleagues discovered a group of galaxies that appeared to lack dark matter. Van Dokkum says that the unexpected and difficult to explain galaxies that they found in the year of 2018) created a lot of controversy and discussion.
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The other galaxies lived in a crowded environment, where bigger, neighboring galaxies frequently fly by. Fraternali's galaxy is pretty isolated, with no neighbors that are as annoying as those in the same area. Van Dokkum says it could be significant. How do you get stars and gas in that location without dark matter?
The objects have been called ultra-diffuse galaxies. They are extreme outliers because they are spread out over vast distances. Some are as large as the Milky Way, but with less stars. They are so close to being transparent that they are difficult to spy on. They are difficult to detect because they are fainter in the center. Mireia Montes, an astronomer at the Space Telescope Science Institute in Baltimore, says that better telescopes and deeper observations have made them more well known.
Vera Rubin and others first showed the existence of unseen dark matter in the 1960s by measuring how fast stars in the center whirl around the center. Scientists calculated how much mass the galaxy must have to keep it in constant motion, rather than being thrown into space. The mass was much larger than the stars. The problem was solved by inferring the presence of dark matter, which doesn't emit or reflect light, and which must be making up the rest of the mass that's holding the galaxy together.
