"Once galaxies get big enough, they start to rely on getting more matter from the cannibalism of smaller galaxies. "So it affects how much gas they've got by the time they merge, which then will affect the evolution of the big system as well. "Often they only survive for one to two billion years and then they'll end up merging with the central one," Dr Stevens said. "That may end up eventually raining down onto the bigger galaxy, or it might end up just staying out in its surroundings," he said.īut in most cases, the little galaxy is doomed to merge with the larger one anyway. The team's finding fits with previous evidence that suggests satellite galaxies have lower star formation rates.ĭr Stevens said stripped gas initially goes into the space around the larger galaxy. "That's why it was the best sample to do this analysis." "These are the deepest observations and largest sample of atomic and molecular gas in the local Universe," she says. They then took the actual observations from the telescopes and compared them to their original predictions.Īssociate Professor Catinella, who led the Arecibo survey of atomic gas, says the IRAM 30-meter telescope observed the molecular gas in more than 500 galaxies. Ram pressure stripping due to the pressure 50 51exerted by the intergalactic medium on the galaxy interstellar medium is considered the most e cient of such processes4. The research team took a state-of-the-art cosmological simulation and made direct predictions for the amount of atomic and molecular gas that should be observed by specific surveys on the Arecibo telescope in Puerto Rico and the IRAM 30-meter telescope in Spain. Molecular gas is very difficult to detect directly. The research was a global collaboration involving scientists from the University of Maryland, Max Planck Institute for Astronomy, University of Heidelberg, Harvard-Smithsonian Center for Astrophysics, University of Bologna and Massachusetts Institute of Technology. "This fast-acting process is known as ram pressure stripping." "And when a galaxy moves through the hot intergalactic medium or galaxy halo, some of the cold gas in the galaxy is stripped away.
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