For decades, the most distant objects we’ve seen were quasars. We now know that these are powerful active black holes. Active galactic nuclei are so distant that they resemble star-like points of light. This tells us that supermassive black holes in the early universe may have been powerful monsters driving the evolution of their galaxies. We thought most of the first supermassive black holes went through such an active phase, but a new study shows that most supermassive black holes don’t go through such an active phase.

Most galaxies have a supermassive black hole. They contain millions or billions of solar masses. They can launch huge jets of ionized gas that rush out of the galaxy at nearly the speed of light, smash stars to seed the galaxy with gas and dust, and even dust the galaxy to encourage star formation. They can also remain silent for billions of years, hiding in the galaxy’s central bulge, just like the black hole at the center of the Milky Way. But the massive mass of these black holes suggests that they grew rapidly in their youth; this suggests a period of extreme activity similar to distant quasars.

This new study looks at a period in cosmic history known as cosmic noon. This is the era when the universe is about 3-6 billion years old and star formation in the universe is at its peak. This is also when we expect supermassive black holes to be active, as their churning of gas and dust could trigger star formation. Using the James Webb Space Telescope, the team collected data from a region of the sky known as the Extended Groth Strip (ESG).

ESG is a small barren patch of sky between the constellations Ursa Major and Ursa Major. More than 50,000 galaxies were discovered by the Hubble Space Telescope in detail in 2004 and 2005. In 2011, the Spitzer Space Telescope observed this region in the infrared wavelength range as part of the Extended Groth Strip International Survey (AEGIS). Spitzer saw the glow of many active black holes, but not as much as expected. This was hardly surprising as the Spitzer might not be sensitive enough to see smaller AGNs or AGNs covered in deep dust.

This new survey by JWST expected more but did not meet expectations. The Early Release Science of Cosmic Evolution (CEERS) program has found approximately the same number of active black holes as before. Thanks to JWST’s higher resolution and sensitivity, we can ignore the findings.

This team found that active black holes are rare at cosmic noon, meaning that most galactic black holes grow more slowly. The team also found that smaller galaxies do not contain very large amounts of dust. Most of the galaxies observed were similar to the Milky Way. Spiral galaxies with a limited amount of dust and a black hole at the center. This shows that there has never been an AGN period in our galaxy. It’s worth noting that this initial result is only valid for about 400 galaxies. The team plans to complete a larger survey of 5,000 galaxies next year. Source