There comes a time in every galaxy’s life, astronomers think, when the galaxy ejects a large part of its gas, but scientists aren’t certain what drives this “mid-life crisis.”
When that gas ejection happens, a galaxy loses the material it needs to form new stars. A galaxy’s younger, bluer stars will start to age out and die, giving away to older, smaller, redder stars. And researchers at New York University Abu Dhabi wondered whether the supermassive black hole at a galaxy’s center might be responsible, so they examined how a black hole’s activity helps a galaxy throw out some of its gas.
“The connection between the activity of [supermassive black holes] and the ejection of gas from the entire galaxy is poorly understood,” Aisha Al Yazeedi, a research scientist at New York University Abu Dhabi and lead author of the paper, said in a statement.
The researchers focused on one galaxy, MaNGA 1-166919. (“MaNGA” here indicates that the galaxy was part of a survey called “Mapping Nearby Galaxies at APO” that, well, mapped nearby galaxies.)
MaNGA 1-166919 is of particular interest since it has what astronomers call an active galactic nucleus: a center that’s particularly bright thanks to a supermassive black hole’s disk bursting with energy, often in a pair of searchlight-like jets that shoot away from the galactic center in two directions.
By watching the galaxy with both radio waves and visible light, the researchers found that those two jets of the supermassive black hole were, indeed, driving gas out of the galaxy. The scientists also found evidence that the outflow of gas was playing with star formation: accelerating it in some areas and quenching it in others.
Further research can tell us not just about the future of MaNGA 1-166919 but also about the future of our own neighborhood: the Milky Way and our nearby Andromeda Galaxy may both be undergoing the mid-life crisis that will turn them into older, redder galaxies.
The research is described in a paper published Aug. 4 in The Astrophysical Journal.
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