James Webb Space Telescope The survey reveals fewer supermassive black holes than was assumed
A University of Kansas survey of a swath of the universe using the James Webb Space Telescope has revealed active galactic nuclei — supermassive black holes that are rapidly increasing in size — that are rarer than many astronomers previously assumed.
The findings, made with JWST’s Medium Infrared Instrument (MIRI), suggest that our universe may be a little more stable than assumed. The work also provides insight into observations of faint galaxies, their properties, and challenges in defining AGNs.
A new paper detailing the JWST research, conducted under the auspices of the Cosmic Evolutionary Early Release Science (CEERS) program, was recently made available at arXiv Prior to the publication of the official peer review in the Astrophysical Journal.
The work, which was headed by Alison Kirkpatrick, assistant professor of physics and astronomy at Kuwait University, focused on a long-studied region of the universe dubbed the Groth Bar, which lies between the constellations Ursa Major and Boötes. However, previous examinations of the region relied on a less powerful generation of space telescopes.
“Our observations were made last June and December, and we aimed to describe what galaxies looked like during the peak of star formation in the universe,” Kirkpatrick said. “This is a look back in time from 7 to 10 billion years in the past. We used the mid-infrared instrument on the James Webb Space Telescope to look at dust in galaxies that existed 10 billion years in the past, and this dust can mask the formation process. persistent stars, and it can hide growing supermassive black holes.So I conducted the first survey to look for these supermassive black holes lurking in the centers of these galaxies.
Results and implications
While each galaxy is characterized by the presence of a massive mass Black hole And in the middle are the more exciting active nuclei, which are more exciting perturbations that attract gas and exhibit a luminosity absent from typical black holes.
Kirkpatrick and several fellow astrophysicists predicted that the higher-resolution survey by the James Webb Space Telescope would locate many more active active galaxies than the previous survey with the Spitzer Space Telescope. However, even with MIRI’s boost in power and sensitivity, a few additional AGNs were found in the new survey.
“The results looked completely different from what I expected, which led to my first big surprise,” Kirkpatrick said. “One of the important discoveries was the rarity of fast-growing supermassive black holes. This discovery raised questions about where these objects might be located. As it turns out, these black holes are likely to grow at a slower rate than previously thought, which is interesting, given that the galaxies I examined similar to our galaxy. milky way from the past. Previous observations with Spitzer have allowed us to study brighter, more massive galaxies that contain rapidly growing supermassive black holes, making them easier to spot.
An important puzzle in astronomy, Kirkpatrick said, is understanding how typical supermassive black holes, such as those found in galaxies like the Milky Way, grow and affect their host galaxy.
She said: “The results of the study indicate that these black holes do not grow rapidly, absorb limited material, and may not significantly affect their host galaxies.” “This discovery opens up a whole new perspective on the growth of black holes since our current understanding is largely based on the more massive black holes in the largest galaxies having large effects on their hosts, but it is likely that smaller black holes in these galaxies have a significant impact.” no.”
Another surprising finding, said the Kuwait University astronomer, is the absence of dust in these galaxies.
“With the James Webb Space Telescope, we can identify much smaller galaxies than ever before, including those as big as the Milky Way or even smaller, which was previously impossible at these redshifts (cosmic distances),” Kirkpatrick said. “Typically, more massive galaxies contain abundant dust due to rapid star formation rates. I had assumed that lower-mass galaxies would also contain large amounts of dust, but they did not, which defies my expectations and makes another interesting discovery.
According to Kirkpatrick, this work changes the understanding of how galaxies grow, especially in relation to the Milky Way.
“Our black hole appears to be completely calm, not showing much activity,” she said. “One of the important questions regarding the Milky Way is whether it is active or has gone through an AGN phase. If most galaxies, like our own, lack detectable AGNs, this could mean that our black hole was not more active in the past. Ultimately, this knowledge will help constrain and measure the masses of black holes, and shed light on the origins of black hole growth, which remain an unanswered question.
Reference: “CEERS Principal Paper VII: JWST/MIRI Reveals Few Galaxies in Cosmic Noon Unseen by Spitzer” by Allison Kirkpatrick, Guang Yang, Aurelian Le Bell, Greg Troiani, Eric F Bell, Nico J. Cleary, David Elbaz, Stephen L. Finkelstein, Nimish B. Hathi, Michaela Hirschmann, Ben W. Holwerda, Dale D. Koszewski, Ray A. Lucas, Jade McKinney, Casey Babovic, Pablo J. Perez Gonzalez, Alexandre de la Vega, Michaela B. Bagley, Emmanuel Daddy, Mark Dickinson, Henry C. Ferguson, Adriano Fontana, Andrea Grazian, Norman A. Grosjean, Pablo Arrabal Haro, Jehan S. Kartaltepe, Lisa J. Kelly, Anthony M. Cookmuir, Jennifer M. Lutz, Laura Pinterici, Noor Perezkal, Swara Ravindranath, Rachel S. Somerville, Jonathan R. Trump, Stephen M. Wilkins, L.A., Aaron Young, presenter. Astrophysical Journal.
Kirkpatrick was recently awarded a new senior time at JWST to conduct a larger field survey of the Extended Groth Strip using MIRI. Her current paper included about 400 galaxies. Its upcoming survey (MEGA: MIRI EGS Galaxy and AGN Survey) will include about 5,000 galaxies. The work is scheduled to take place in January 2024.
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