JWST images show a supermassive black hole in the early universe, notable for its enormous size compared to the host galaxy and shrouded in thick dust.

from Ben-Gurion University of the Negev. By analyzing images from the James Webb Space Telescope (JWST), a team of astronomers led by Lucas Furtak and Professor Adi Zitrin discovered an extremely red, supermassive black hole with gravitational lenses in the early universe. . Its colors indicate that the black hole lies behind a thick shroud of dust that blocks most of its light. The team was able to measure the mass of the black hole and found that it was significantly larger compared to its host galaxy than seen in more local samples. The finding was published on: Nature two weeks ago.

JWST: Unlocking the Secrets of the Early Universe

Launched two years ago, JWST revolutionized our view of the early formation of galaxies. This has led to the discovery of very old galaxies with greater abundance and brightness than previously thought, and has revealed some new types of objects.

A quasar-like discovery

A team of astronomers has discovered what appears to be a lensed quasar-like object from the early universe in JWST images. Quasars are bright active galactic nuclei: supermassive black holes that actively accrete material at the centers of galaxies.

Gravitational lensing force

The accretion of material onto the black hole emits large amounts of radiation that illuminates the host galaxy, resulting in a compact and bright star-like galaxy. The JWST images in which Furtak and Zitrin identified the object were taken for the UNCOVER program (IP: Ivo Labbe of Swinburne University of Technology and Rachel Besançon of the University of Pittsburgh), which is imaging the galaxy cluster domain Abel 2744 at an unprecedented speed. depth. Because the cluster contains so much mass, it bends space-time or the paths of light rays passing near it, effectively forming a gravitational lens. Gravitational lensing magnifies background galaxies and allows astronomers to observe galaxies much further away than would normally be possible.

red dot phenomenon

“We were very excited when JWST started sending out its first data. “We were scanning incoming data for the UNCOVER program, and three very compact but red blooming objects stood out and caught our attention,” said Dr. Lucas Furtak, BGU postdoctoral researcher and lead author of the discovery paper. “The red dot appearances immediately led us to suspect that it was a quasar-like object.” happened.”

solve the mystery

Furtak began exploring the object with the UNCOVER group. “Using the digital lensing model we created for the galaxy cluster, we determined that the three red dots must be multiple images of the same background source seen when the universe was only 700 million years old,” says astronomer Professor Zitrin. BGU and one of the lead authors of the discovery papers.

A large-scale breakthrough

“Analysis of the object’s colors showed that it is not a typical star-forming galaxy. This further supports the hypothesis of a supermassive black hole,” says Professor Rachel Besanson of the University of Pittsburgh and co-director of the UNCOVER program. “With its compact size, it became clear that this was probably a supermassive black hole, but it was still different from other quasars found in those early times,” Professor Besançon said. he added. The discovery of a unique red and compact object was published last year. Astrophysical Journal . But this was only the beginning of the story.

Spectral ideas and surprises

The team then acquired JWST/NIRSpec data from three “red dot” images and analyzed the data. “Spectra was simply stunning,” says Ivo Labbe, co-director of the UNCOVER program and Professor at Swinburne University of Technology. — The resulting spectrum due to the combination of the signal from the three images with the magnification of the lens is equivalent. JWST observations of an unlensed object extend to approximately 1,700 hours, making it the deepest spectrum obtained by JWST for a single object in the early universe,” says Professor Labbe.

“Using the spectrum, we not only confirmed that the red compact object is a supermassive black hole and precisely measured its redshift, but also obtained a precise estimate of its mass based on the width of its emission lines,” says the lead author. Dr. “The gas rotates in the gravitational field of the black hole and reaches very high speeds that are not observed in other parts of galaxies. Due to the Doppler shift, the light emitted by the accumulated material shifts to red on one side and blue on the other, depending on its speed. This causes the emission lines in the spectrum to further broaden,” Furtak said. “

eclipsed galaxy

But the measurement led to another surprise. Nature two weeks ago: The mass of the black hole appears to be extremely high compared to the mass of its host galaxy.

“All the light of this galaxy needs to fit into a small region about the size of a modern star cluster. Magnifying the source by gravitational lensing gave us clear constraints on size. Professor Jenny Green of Princeton University said: “Even if all possible stars were packed into such a small region, the black hole It accounts for at least 1% of the total mass of the system,” the paper says. “In fact, some other supermassive black holes in the early universe have been found to exhibit similar behavior; “This has led to some intriguing insights into the growth of the black hole and its host galaxy and the poorly understood interactions between them.”

A cosmic chicken-and-egg dilemma

Astronomers don’t know whether such supermassive black holes grow from the remnants of stars, for example, or from material that collapsed directly into black holes in the early universe.

“In a way, this is the astrophysical equivalent of the chicken and egg problem,” says Professor Zitryn. “We currently don’t know what came first, the galaxy or the black hole, how big the first black holes were and how they grew.”

Future ideas from JWST

With many such “little red dots” and other active galactic nuclei recently discovered by JWST, we hope to have a better idea soon.