Recent observations made by the James Webb Space Telescope (JWST) have challenged prior expectations by revealing a lower occurrence of rapidly growing supermassive black holes, reshaping our comprehension of these cosmic phenomena.
In most large galaxies, colossal black holes inhabit their centers, and some of these black holes undergo periods of accelerated growth, emitting intense radiation during these phases. These highly active black holes are termed active galactic nuclei (AGNs) and can outshine their entire host galaxies, ranking as the universe's brightest and most enduring sources of light.
In 2017, astronomer Allison Kirkpatrick and her research team made predictions that the JWST, equipped with advanced infrared capabilities, would detect a significant number of AGNs. To validate this forecast, they directed the JWST towards a well-examined region of the sky where the Spitzer Space Telescope had previously identified AGN signatures in about one-third of the 19 galaxies it examined in 2008.
These galaxies, observed around 10 billion years ago during the peak of cosmic star formation, were typically large and radiantly bright. The JWST's heightened sensitivity enabled it to identify fainter galaxies, akin in size to the Milky Way, from the same era. Astonishingly, out of nearly 500 galaxies that had never been previously observed, only 6 percent displayed indications of AGNs, as reported by the research team.
Tonima Tasnim Ananna, an astronomer at Wayne State University in Detroit who was not involved in the study, highlighted the JWST data's revelation of a novel category of galaxies from the distant universe, hitherto beyond reach.
These recently discovered galaxies seem enshrouded in interstellar dust, which could potentially obscure rapidly growing black holes, rendering them challenging to detect with existing technology.
This discovery challenges the prevailing comprehension of black hole and galaxy formation, as AGN phases are considered pivotal for accumulating the colossal mass of supermassive black holes, which can weigh as much as millions or even billions of suns.
Kirkpatrick theorizes that not all galaxies may undergo active phases, implying that certain supermassive black holes might have originated as relatively massive entities rather than evolving from smaller counterparts.
Active black holes not only experience rapid growth but also exert an influence on their host galaxies. The intense heat generated during an AGN phase can impede star formation within the host galaxy by hindering the cooling of gas, a critical process for star formation.
Additionally, the radiation pressure stemming from a rapidly accreting supermassive black hole can produce powerful winds that disrupt the surroundings near the galaxy's center, potentially obstructing the formation of planets capable of sustaining life.
An alternative explanation for the apparent scarcity of active black holes in the new JWST data suggests that these black holes may experience intermittent growth through brief bursts of activity, rendering them nearly undetectable.
To gain deeper insights into the prevalence and behavior of active supermassive black holes, Kirkpatrick intends to conduct an expanded search using the JWST in January, scrutinizing approximately 4,000 galaxies.