Simulation of Large-Scale Galactic Structures
Illustris Collaboration/ESO
A cosmic network is disrupting a galaxy’s star-forming abilities. Galaxies require gas to generate stars, and a distant dwarf galaxy, nearly 100 million light-years away, is being deprived of this essential material by an expansive web of cosmic constituents.
While one half of the galaxy known as AGC 727130 seems relatively normal, its opposite side shows gas stretching well beyond its perimeter, being torn apart by unseen forces. Researchers from Columbia University in New York identified this collapsing galaxy utilizing the Very Large Array, a radio observatory situated in New Mexico Nicholas Luber.
Even though AGC 727130 is in proximity to two other dwarf galaxies, the researchers concluded that it isn’t close enough to engage with them in a way that would create turbulent gas. Their findings imply that the gas is expelled through a mechanism known as ram pressure stripping. This occurs when a galaxy traverses an intragalactic cloud—in this case, part of the cosmic web—leaving behind its gas. Without this gas, galaxies become “quenched” and are unable to create new stars.
The filamentous structures in the cosmic web are so slender that it would likely take more than one filament to strip gas from a galaxy, yet AGC 727130 resides at the junction of multiple filaments. “The concept that a cosmic web could extract gas from galaxies through collisional pressure is not surprising and likely happens frequently, but it’s challenging to confirm,” states Luber. “We were fortunate to observe this phenomenon.”
Identifying such galaxies poses a challenge because the gas removal is a gradual process, and galaxies that have already lost their gas tend to be exceedingly faint. “What’s intriguing about this outcome is that low-mass extinguished dwarf galaxies are exceptionally rare; only a few, less than 0.06 percent, are believed to exist without a substantial host galaxy,” comments Julia Blue Bird, a radio astronomer based in New Mexico.
Even among that limited number of extinguished dwarf galaxies, only a scant few have had their gas stripped by the cosmic web rather than through interactions with other galaxies. “This might be… the first definitive case of such an occurrence,” remarks Jacqueline Van Gorcom from Columbia University. Several large radio telescopes are poised to unveil new gas maps across extensive regions of the universe, which could provide additional insights regarding these galaxies.
This discovery is crucial in addressing a cosmological dilemma known as the missing satellite problem. Current cosmological models suggest there should be significantly more dwarf galaxies orbiting larger ones than we currently observe. “We struggle to find many quenched dwarfs; is it because they’re hard to detect, or are they simply not present? This suggests that quenching may also be occurring far from larger galaxies,” states team member Sabrina Stierwalt from Occidental College in California. Uncovering additional galaxies quenched by the cosmic web could help reconcile discrepancies between model predictions and actual observations.
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Source: www.newscientist.com
