A team led by Yongda Zhu reports that intense radiation from an active supermassive black hole can slow star formation in its host galaxy and in neighboring galaxies millions of light-years away. The finding appears in The Astrophysical Journal Letters after observations of a very luminous quasar.
Using the James Webb Space Telescope, the researchers measured emission from ionized oxygen, O III, which traces very recent star formation. They compared O III emission with ultraviolet light in galaxies near the quasar and found that galaxies within about a million-light-year radius showed weaker O III relative to their ultraviolet light. The team interprets this as suppressed recent star formation.
Zhu explains that during the quasar phase the black hole emits strong radiation and heat that can split 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 now plans to test whether the phenomenon is common across multiple quasar fields and to study other factors that might affect nearby galaxies.
Difficult words
- supermassive black hole — very large space object with strong gravity
- quasar — very bright active center of a galaxy
- ionized oxygen — oxygen atoms that lost some electrons
- O III — a label for ionized oxygen emission
- ultraviolet — light with shorter wavelength than visible
- molecular hydrogen — two hydrogen atoms joined as gas
- suppress — to make something happen lesssuppressed
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could less recent star formation change the appearance of a galaxy over time?
- What other factors would you study to understand changes in nearby galaxies?
- How can telescopes like the James Webb Space Telescope help scientists study these effects?
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