A team of scientists using the Arecibo radio telescope measured the hydrogen content of 250 galaxies located in different environments to show that galaxies in groups have less gas than galaxies found in isolation.
“What drives the gas in and out of galaxies is one of the most outstanding open questions in extragalactic astronomy,” said Dr Barbara Catinella from Swinburne University of Technology, who is a lead author of the paper published in the Monthly Notices of the Royal Astronomical Society (arXiv.org).
Astronomers have known for decades that spiral galaxies located in clusters have less gas and star formation than similar, isolated galaxies. Clusters are much larger density concentrations, containing several hundred or even thousands of galaxies immersed in the so-called intergalactic medium.
“When a galaxy moves through this hot medium, most of its hydrogen gas can be easily removed,” said co-author Dr Luca Cortese of Swinburne University of Technology and European Southern Observatory.
“We know that gas is removed from galaxies that are located in the harsh cluster environment, but this is the first time that we witness similar effects in the more friendly groups. This was an exciting result, which opened up more questions than it solved.”
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