by Like being caught within a spider’s web the world of flight changes dramatically, galaxies enveloped in the vast cosmic web undergo a major irreversible change.
Now, scientists from the University of Kansas aim to better understand the mechanisms at play in shaping galaxy clusters as they travel through a cosmic web of different environments.
KU professor of physics and astronomy Gregory Rudnick is leading the effort, which involves recreating the cosmic web in a computer simulation, then studying the gas content and star-forming properties of galaxies as they move through the web. that. The effort will use images of approximately 14,000 galaxies from DESI’s Legacy Survey, the Wide-field Infrared Survey Explorer (WISE) and NASA’s Galaxy Evolution Explorer (GALEX); The team will collect additional observations with the 0.7-m Planewave Siena telescope.
“The main objective of this project is to understand the influence of environmental factors on the transformation of galaxies,” Rudnick said in a statement. “In the universe, galaxies are scattered in a non-uniform distribution characterized by different densities. These galaxies are aggregated in large clusters, which include hundreds and thousands of galaxies, as well as smaller groups, which contain thousands and hundreds of galaxies. “
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Galaxies can sit in clusters or groups, or they can reside in more remote and lower-density regions of the universe called “the field,” Rudnick said.
Although previous studies that simulated the cosmic web and galaxies within it compared galaxies in clusters and groups to those alone in the field, they neglected the elongated filamentary structures of gas, dust and stars that link the type clustered.
Rudnick and his colleagues focused on this cosmic highway, focusing on the filamentary environments that galaxies experience, how the galaxies are oriented into groups and clusters in the first place, and how the filaments affect their evolution.
“Galaxies follow a path into these filaments, experiencing a dense environment for the first time before progressing into groups and clusters,” Rudnick said. “Studying galaxies in filaments allows us to examine the initial encounters of galaxies with dense environments.”
Most galaxies that enter the “urban centers” of clusters, Rudnick said, do so along cosmic web “superhighways,” with a small number taking “rural routes” that lead them into the clusters and groups. not interacting much with their environment.
“Although filaments are like intersecting highways, these less-traveled routes into dense regions are similar to the analogy of driving on rural roads in Kansas to access city limits,” Rudnick said. “Galaxies can exist in filaments or be in groups that live in filaments like beads on a string. In fact, most galaxies in the universe are within groups.”
The team hopes that, with this simulation, it will be possible to gain an insight into the emergence of environmental effects on galaxies and to decode how galaxies behave in the filaments and the most common groups that find.
Galaxies trapped birth stars
One key aspect of the KU team’s work is to assess how the conditions of the cosmic web filaments affect the processing of gas in overdensity pockets, which scientists call the “baryon cycle”.
Because stars are born when clumps of gas and dust collapse too close together, disrupting the baryon cycle can boost or block star formation, speeding up or slowing down the growth of galaxies.
“There is gas in the space between galaxies. In fact, most of the atoms in the universe are in this gas, and that gas can accumulate on the galaxies,” said Rudnick. “This intergalactic gas is transformed into stars, although the efficiency of this process is relatively low, with only a small percentage contributing to star formation. Most is expelled in the form of large winds.”
Some of these winds become outflows that blow galaxies back into space, while other wind material falls back to its galaxy of origin, where it is finally accumulated and recycled as part of the baron cycle.
“Galaxies can be conceptualized as baron processing engines, pulling gas from the interstellar medium and turning some of it into stars,” Rudnick explained. “The stars then go supernova, producing heavier elements. Some of the gas is blown out into space, forming a galactic jet that eventually falls back into the galaxy.”
When galaxies encounter a dense environment in the cosmic web, they can change their internal pressure and disrupt the baron cycle by removing gas from the galaxy or its future gas supply.
This results in Galactic star factories, which sit at the heart of the clusters, slowing to a halt as their star birth material is extinguished.
“The disruption affects the intake and expulsion of gas by galaxies, leading to changes in their star formation processes,” Rudnick said. “While there may be a temporary increase in star formation, in almost all cases, it results in a decrease in star formation.”
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The team’s simulations are expected to help scientists better understand the baron cycle, which the Astro2020 Decadal survey highlighted as a key science topic for the next decade.
The research will also include science outreach to Kansas and New Jersey high school students through 2026. This will include equipping schools with 11 MacBook Pros to allow students to engage with the research project.
