Researchers led by Yongda Zhu report evidence that intense radiation from an active supermassive black hole can suppress recent star formation not only inside its host galaxy but also in neighboring galaxies on intergalactic scales. The result, published in The Astrophysical Journal Letters, comes from observations of one of the most luminous known quasars, J0100+2802.
That quasar is powered by a supermassive black hole roughly 12 billion times the mass of the sun, and its light reaches us from a time when the universe had not yet reached its 1‑billion‑year birthday, more than 13 billion years ago. Using the James Webb Space Telescope, the team measured emission from ionized oxygen (O III), a tracer of very recent star formation, and compared it with ultraviolet light in galaxies near the quasar. Galaxies within a million‑light‑year radius of the bright quasar showed weaker O III emission relative to their ultraviolet light, which the researchers interpret as a sign that recent star formation has been suppressed.
Zhu calls the effect a "galaxy ecosystem" and compares a very active black hole to a dominant predator that changes conditions for others. The proposed mechanism is that quasar radiation and heat can break molecular hydrogen in cold interstellar clouds; molecular hydrogen is the raw fuel for new stars, so breaking it up can quench star formation. The team notes that JWST was essential because the light from these distant objects is stretched into the infrared, and previous telescopes could not detect the faint signals clearly. They plan to survey other quasar fields and study additional factors, and they also raise the question of how a past quasar phase may have influenced the Milky Way.
Difficult words
- suppress — to stop or reduce an activity or processsuppressed
- quasar — a very bright active galactic nucleus
- ionize — to remove or add electrons to atomsionized
- tracer — a sign or measurement that shows presence
- ultraviolet — type of light with shorter wavelengths than visible
- intergalactic — between or among different galaxies in space
- molecular hydrogen — gas made of two bonded hydrogen atoms
- quench — to stop a physical or chemical process
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could a quasar suppressing star formation in nearby galaxies change our view of galaxy evolution?
- What other observations should researchers make in additional quasar fields to test this suppression effect?
- The article suggests a past quasar phase might have influenced the Milky Way. What consequences could that have for our galaxy?
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