Tug-of-War Between Merging Galaxies
ALMA | NRAO | NAOJ | ESO | 2022 Aug 30
While observing a newly-dormant galaxy using the Atacama Large Millimeter/ submillimeter Array (ALMA) and the Hubble Space Telescope (HST), scientists discovered that it had stopped forming stars, not because it had used up all of its gas, but because most of its star-forming fuel had been thrown out of the system as it merged with another galaxy. The result is a first for ALMA scientists. Moreover, if proven common, the results could change how scientists think about galaxy mergers and deaths.
As galaxies move through the Universe, they sometimes encounter other galaxies. As they interact, each galaxy’s gravity pulls on the other. The ensuing tug-of-war flings gas and stars away from the galaxies, leaving behind streams of material known as tidal tails.
And that’s just what scientists believe happened to SDSS J1448+1010, but with a plot twist. The massive galaxy, which was born when the Universe was about half its current age, has nearly completed merging with another galaxy. During observations with the HST and ALMA scientists discovered tidal tails containing roughly half of the entire system’s cold, star-forming gas. The discovery of the forcefully discarded material— equal to 10 billion times the mass of Earth’s Sun— indicated that the merger might be responsible for snuffing out star formation, which scientists didn’t expect. ...
The discovery is shedding light on the processes by which galaxies live or die, and helping scientists to better understand their evolution. ...
Star Formation Suppresion by Tidal Removal of Cold Molecular Gas
from an Intermediate-Redshift Massive Post-Starburst Galaxy ~ Justin S. Spilker et al
- Astrophysical Journal Letters 936(1):L11 (2022 Sep 01) DOI: 10.3847/2041-8213/ac75ea
arXiv > astro-ph > arXiv:2208.13917 > 29 Aug 2022