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upstart writes:

The stream could keep the galaxy supplied with star-forming fuel for a billion years:

A long, cold stream of gas is feeding a very distant galaxy like a vast bendy straw. The finding suggests a new way for galaxies to grow in the early universe, researchers report in the March 31 Science.

Computer simulations predicted that streams of gas should connect galaxies to the cosmic web (SN: 3/6/23). But astronomers expected that gas to be warm, making it unsuitable for star-forming fuel and galaxy growth.

So astronomer Bjorn Emonts and his colleagues were surprised to see a stream of cold, star-forming gas leading into the Anthill Galaxy, a massive galaxy whose light takes 12 billion years to reach Earth.

[...] "People didn't think that these streams could get so cold," says Emonts, of the National Radio Astronomy Observatory in Charlottesville, Va.

But there, in the data, a frigid stream stretched at least 325,000 light-years away from the galaxy. The stream carries the mass of 70 billion suns and deposits the equivalent of about 450 suns in cold gas onto the galaxy every year, the team calculated. That's enough to double the galaxy's mass within a billion years.

[...] If other galaxies are fed by similar structures, it could mean that early galaxies grew mostly by drinking directly from the cosmic streams, rather than by the leading hypothesis — violent galaxy mergers (SN: 6/28/19).

Journal Reference:
Bjorn H. C. Emonts, Matthew D. Lehnert, Ilsang Yoon, et al., A cosmic stream of atomic carbon gas connected to a massive radio galaxy at redshift 3.8, Science, 379, 2023 (DOI: https://www.science.org/doi/10.1126/science.abh2150)

Original Submission