JWST Maps 164,000 Galaxies Across Cosmic Web in 255-Hour COSMOS-Web Survey

Q: How do black holes, famous for devouring matter, actually prevent entire galaxies from forming new stars?

Supermassive black holes shut down star formation not by “eating” an entire galaxy, but by making its star-making gas unusable. When a central black hole is actively feeding, the gas falling toward it forms a hot accretion disk that releases enormous energy as radiation, X-rays, and fast-moving winds. Those outflows can blow cold gas out of the galaxy’s inner regions, shred dense clouds, or heat the gas so much that it can no longer cool and collapse into new stars. Star formation needs cold, dense gas; if that fuel is expelled or kept hot, starbirth stops. That process, known as AGN feedback, is one of the key “mass-related” quenching mechanisms highlighted by the new JWST COSMOS-Web results. The survey found that in the earlier universe, especially up to about 7 billion years ago, massive galaxies were often quenched by internal factors such as very large dark matter halos or active supermassive black holes. New XRISM observations help explain the physics. In the galaxy NGC 4151, researchers detected a direct timing link between black hole X-ray flares and ultra-fast outflows launched from the accretion disk. These winds can reach tens of thousands of kilometers per second, carrying enough energy to scour or overheat the gas reservoir needed for star formation across much of a galaxy. So the black hole’s main role is not simple consumption. It acts more like a galaxy-scale engine that stirs, heats, and ejects the raw material stars need, leaving the galaxy “quenched.”

3 articles · Updated · Livescience.com · Jul 6

A 164,000-galaxy catalog from JWST’s COSMOS-Web survey let astronomers reconstruct the universe’s large-scale “skeleton” and trace galaxy evolution back roughly 13 billion years.
The 255-hour program covered a sky area about the size of three full moons, delivering sharper redshift measurements and revealing fainter, lower-mass and more-distant galaxies than earlier COSMOS2020 maps.
The new map shows dense regions fueled rapid galaxy growth in the early universe but later became linked to quiescent, star-dead massive galaxies, tying the cosmic web directly to changing star-formation patterns.
Researchers said mass-driven quenching dominated until about 7 billion years ago, when trillion-solar-mass halos and active black holes heated gas; in the more recent universe, environment became the main brake on star formation.
The publicly released catalog pushes cosmic-web mapping to when the universe was only a few hundred million years old, extending a framework for studying how structure shaped galaxies over cosmic time.

Sources

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How do black holes, famous for devouring matter, actually prevent entire galaxies from forming new stars?

Mapping 164,000 Galaxies: JWST’s COSMOS-Web Survey Unveils the Universe’s Largest-Ever Cosmic Web in Unprecedented Detail

Overview

The James Webb Space Telescope (JWST) has launched a new era in cosmic exploration with the COSMOS-Web survey, its most detailed mapping project yet. Led by researchers at the University of California, Riverside, astronomers created the most intricate map of the cosmic web, tracing its structure back to when the universe was just one billion years old. This breakthrough offers a major leap in understanding the universe’s large-scale architecture and evolution. Building on previous research, the COSMOS-Web map provides new insights and strong confirmation of dark matter’s crucial role in shaping the universe’s grandest structures.

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