Far out cosmology: growing giant early galaxies (Introduction)

by David Turell , Wednesday, February 24, 2021, 19:27 (1366 days ago) @ David Turell

Getting eough cold gas:

https://phys.org/news/2021-02-cold-gas-pipelines-early-massive.html

"To come into being, galaxies need a steady diet of cold gases to undergo gravitational collapse. The larger the galaxy, the more cold gas it needs to coalesce and to grow.

"Massive galaxies found in the early universe needed a lot of cold gas—a store totaling as much as 100 billion times the mass of our sun.

"But where did these early, super-sized galaxies get that much cold gas when they were hemmed in by hotter surroundings?

"In a new study, astronomers led by the University of Iowa report direct, observational evidence of streams of cold gas they believe provisioned these early, massive galaxies. They detected cold gas pipelines that knifed through the hot atmosphere in the dark matter halo of an early massive galaxy, supplying the materials for the galaxy to form stars.

"About two decades ago, physicists working with simulations theorized that during the early universe, cosmic filaments ferried cold gas and embryonic, node-shaped galaxies to a dark matter halo, where it all clumped together to form massive galaxies. The theory assumed the filaments would need to be narrow and densely filled with cold gas to avoid being peeled off by the hotter surrounding atmosphere.

***

"Crucially, the researchers located two background quasars that are projected at close angular distances to the target galaxy, much like how Jupiter and Saturn's motion drew them closer to each other when viewed from Earth during the Great Conjunction last December. Due to this unique configuration, the quasars' light penetrating the halo gas of the foreground galaxy left chemical "fingerprints" that confirmed the existence of a narrow stream of cold gas.

"Those chemical fingerprints showed the gas in the streams had a low concentration of heavy elements such as aluminum, carbon, iron, and magnesium. Since these elements are formed when the star is still shining and are released into the surrounding medium when the star dies, the researchers determined the cold gas streams must be streaming in from outside, rather than being expelled from the star-making galaxy itself.

"'Among the 70,000 starburst galaxies in our survey, this is the only one associated with two quasars that are both nearby enough to probe the halo gas. Even more, both quasars are projected on the same side of the galaxy so that their light can be blocked by the same stream at two different angular distances." Fu says. "So, I feel extremely fortunate that natureprovided us this opportunity to detect this major artery leading to the heart of a phenomenal galaxy during its adolescence.'"

Comment: The Milky Way is a giant galaxy, and this tells us how it formed.