Scientists say it is now possible to use the gravitational pull between two merging galaxies to understand why one of them stops forming stars, and is providing new insights into how galaxies die.
“Dead” galaxies are defined as those in which star formation has stopped, and scientists believe that death occurs in very old galaxies when all their star-forming gas content is used up, or following very violent events.
But an international research team including eight universities described in a recent study published Tuesday in the Astrophysical Journal Letters a new way for galaxies to die by merging with other galaxies, which is strongly expelled. star-forming gases In which.
“Previously astronomers believed that the only way to prevent galaxies From the formation of stars it was through really violent and rapid processes, such as the explosion of the great star cluster in the galaxy to extinguish most of the gas in it and heat the rest… Our new observations show that stopping star formation does not require a “resonant” process. The much slower fusion process might also put an end to the formation of stars and galaxies.”
The new study centers on the galaxy SDSS J1448 + 1010, which piqued the team’s interest because it stopped looking at formation Stars are apparently regarding 70 million years old, according to Dr. Spilker, who said, “Simply put, continuing star formation suits most galaxies.”
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But the aforementioned galaxy is also regarding to finish merging with another galaxy, so researchers took a closer look at the galaxy using the Hubble Space Telescope and the Atacama Large Millimeter Observatory Array, ALMA for short, an array of radio telescopes located in Chile.
What the scientists discovered were streams of material from the studied galaxy that they believe was ejected from it during the collision with the second galaxy. Such currents, known as tidal tails, have been observed around other galaxies approaching each other before the merger, and are the result of the gravitational pull between the two galaxies’ massive groups of stars and gas.
But in the case of SDSS J1448 + 1010, the gravitational pull appears to have been so violent that nearly all of the galactic stock needed for future star formation has been expelled, and the amount of gas is greater than the mass of 10 billion suns.
Dr. Spilker said: “Our observations using ALMA and the Hubble telescope prove that the real reason the galaxy stopped forming stars is that the merger process released regarding half of the gaseous fuel needed for star formation into the space between the two galaxies… Without the fuel, the galaxy would not be able to continue. in star formation.
While the discovery hints at the possibility of a new path for galaxies dying, it is only one observation, and it is not yet clear whether the extinction of star formation due to galactic mergers is a common occurrence in the universe, or is a single event limited to the galaxy in question.
“In this galactic-annihilating fusion system, it’s very clear that the cold gas may eventually be expelled very far…the ejection of the cold gas is a new part,” said David Seton, a University of Pittsburgh graduate student in astronomy and a co-author of the study. It’s an interesting galactic fading puzzle, and we’re excited to try to find more examples of it.”