A study from the James Webb Space Telescope reveals that there are fewer supermassive black holes than previously thought.

A study of part of the universe by the University of Kansas using the James Webb Space Telescope found that active galactic nuclei (AGNs), or supermassive black holes that are rapidly increasing in size, have long been thought by many astronomers. It turns out to be rarer than it used to be. Findings from JWST’s Mid-Infrared Observatory (MIRI) suggest that our Universe may be slightly more stable than previously thought. This study also provides insight into observations of faint galaxies, their properties, and challenges in identifying AGNs. A new paper detailing his JWST research, conducted under the auspices of the Cosmic Evolution Early Release Science (CEERS) program, is now available on arXiv ahead of formal peer-reviewed publication in the Astrophysical Journal.

Led by Alison Kirkpatrick, assistant professor of physics and astronomy at KU, the study focused on a long-studied zone of the universe called the Extended Gross Strip, located between the constellations Ursa Major and Bootes. . But previous research in this area has relied on less powerful generations of space telescopes. “Our observations were made in June and December last year and we wanted to characterize what galaxies look like at the height of star formation in space,” Kirkpatrick said. “This is a look back seven to ten billion years ago. The dust can hide ongoing star formation and hide growing supermassive black holes. So I did my first search for supermassive black holes lurking in the centers of these galaxies. ”

Although there is a supermassive black hole at the center of every galaxy, AGNs are the more spectacular cataclysms, actively attracting gas and exhibiting brilliance not found in typical black holes. Kirkpatrick and many other astrophysicists expected that the higher resolution of his JWST survey would discover far more of his AGN than previous surveys conducted with the Spitzer Space Telescope. Ta. However, despite MIRI’s improved performance and sensitivity, new investigations found few additional his AGNs.

“The results were completely different from what I expected, which led to the first big surprise,” Kirkpatrick said. “A key discovery was the rarity of rapidly growing supermassive black holes. This discovery raised questions about the whereabouts of these objects. It’s likely growing more slowly than it did, which is interesting given the fact.” The galaxies I’ve studied resemble the Milky Way of the past. So far, Spitzer’s observations have been able to study only the brightest and most massive galaxies with rapidly growing supermassive black holes, making them easy to find. ” Kirkpatrick said a key mystery in astronomy is understanding how the typical supermassive black holes found in galaxies like the Milky Way grow and affect their host galaxies. Stated. “The results of our study suggest that these black holes are not growing rapidly, may only absorb limited material, and may not have a significant impact on their host galaxies,” she said. Stated. “This discovery opens up an entirely new perspective on the growth of black holes, because our current understanding is largely based on the most massive black holes in the largest galaxies that have a significant impact on their hosts. , but the smaller black holes in these galaxies probably do.” “

Another surprising finding is the absence of dust in these galaxies, said KU astronomers. “Using the JWST, we are able to identify much smaller galaxies than ever before, including galaxies the size of the Milky Way or smaller. It wasn’t possible before with translocation (space distances),” Kirkpatrick said. “Usually, the most massive galaxies have a lot of dust because they form stars faster. I thought low-mass galaxies would also have a lot of dust, but that’s not the case. It was a new and interesting discovery that exceeded my expectations.” Kirkpatrick said the study is changing our understanding of how galaxies grow, especially when it comes to the Milky Way. “Our black hole appears to be fairly calm and not very active,” she said. “An important question about the Milky Way Galaxy is whether it was once active, or whether it went through an AGN phase. If most galaxies, like ours, have no detectable AGN, that is. It could mean that our black holes have never been so active in the past, and this knowledge allows us to limit and measure the mass of black holes, which remains an open question.

source: JWST/MIRI Reveals a Faint Population of Galaxies at Cosmic Noon Unseen by Spitzer, arXiv (2023). DOI: 10.48550/arxiv.2308.09750