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Nasa's James Webb Space Telescope (JWST) has made groundbreaking observations of the light from stars surrounding some of the earliest supermassive black holes in the universe, as they existed less than a billion years after the Big Bang. These findings come from a research team at the Massachusetts Institute of Technology (MIT), who are exploring the rapid growth of these cosmic titans that anchor the hearts of galaxies and are as massive as millions or even billions of suns.
The observations target the puzzle of how these supermassive black holes, observed feeding insatiably on material surrounding them, managed to acquire such immense masses so quickly. This process lights up their accretion disks, powering the luminous quasars at the centers of active galaxies—some of which shine brighter than all the stars in their galaxies combined, a report in Space.com said.
This conundrum is intensified by the fact that supermassive black holes are seen so early in the universe’s 13.8 billion-year history, suggesting a rapid formation that current theories, like continuous black hole mergers, cannot fully explain. The MIT team's use of the JWST to observe faint stellar light from six ancient quasars has provided new evidence supporting the theory that these black holes grew from "heavy seed" black holes.
“These black holes are billions of times more massive than the sun, at a time when the universe is still in its infancy,” explained Anna-Christina Eilers, an assistant professor of physics at MIT. She suggests that "supermassive black holes might have gained their mass before their host galaxies did, and the initial black hole seeds could have been more massive than today."
The intense brightness of quasars, which led to their initial misidentification as star-like points in the 1960s, is now known to stem from massive amounts of matter accreting to supermassive black holes at the centers of galaxies. The JWST’s capabilities have now allowed researchers to differentiate the light of these quasars from the fainter stellar light, solving a problem akin to spotting the light of fireflies on a lighthouse from a mile away, the Space.com report said.
By analyzing the light emissions from the quasars over various wavelengths, the team, including postdoc Minghao Yue from MIT's Kavli Institute for Astrophysics and Space Research, could determine the mass distribution in these early galaxies. “We are able to reveal the light from these stars by very carefully modeling JWST's much sharper images of those quasars,” Yue stated.
Their results indicate that the supermassive black holes are about 10% as massive as the stars in their galaxies—a significant figure when compared to modern galaxies where black holes are just 0.1% the mass of their stars. “This tells us something about what grows first: Is it the black hole that grows first, and then the galaxy catches up? Or is it the galaxy and its stars that first grow, and they dominate and regulate the black hole’s growth?” Eilers posed.
The findings, published in the Astrophysical Journal, hint at a universe where black holes grew rapidly and possibly before their galaxies, providing tantalizing evidence of how these cosmic behemoths came to be.
