Researchers from Michigan State University (MSU) have made groundbreaking discoveries about the supermassive black hole at the center of the Milky Way known as Sagittarius A* (Sgr A*).
Using ten years of X-ray data from NASA’s NuSTAR telescopethese findings provide new insights into the enigmatic environment surrounding this colossal cosmic entity.
Discover hidden flares and echoes
Grace Sanger-Johnson, a postbaccalaureate researcher at MSU, previously discovered nine unnoticed x-rays by Sagittarius A* by painstakingly analyzing ten years of data. These bursts are high-energy eruptions that illuminate the immediate vicinity of the black hole, an area usually shrouded in darkness due to its enormous gravity that not even light can escape.
“We have a front-row seat to observe these unique cosmic fireworks at the center of our own Milky Way Galaxy,” said Shuo Zhang, Sanger-Johnson’s consultant. The outbursts provide a rare opportunity to study the black hole’s environment and better understand the extreme conditions there.
While Sanger-Johnson focused on the torchesJack Uteg, an undergraduate researcher in the MSU Honors College, studied X-ray echoes of a nearby molecular cloud known as “the bridge.” These echoes provide a glimpse into the activities of Sgr. A* in recent centuries.
By examining nearly 20 years of data from NuSTAR and the European Space Agency X-ray Multi-Mirror (XMM). Newton Observatory, Uteg discovered that the cloud’s brightness is likely a delayed reflection of past X-ray bursts. black hole.
“The brightness we see is most likely the delayed reflection of previous X-ray bursts from Sgr A*,” Uteg explains. This analysis helps reconstruct a timeline of the black hole’s past behavior, showing that Sgr A* was significantly more active about 200 years ago.
The significance of these findings
These discoveries are crucial for understanding the dynamic environment at the heart of our Galaxy. Black holes are notoriously difficult to study directly because of their intense gravitational fields, which distort light and other signals.
However, by examining the effects of these fields on the surrounding matter, scientists can deduce important details about them black hole activity. The work of Sanger-Johnson and Uteg exemplifies this approach, shedding light on both the immediate and historical behavior of Sgr. A*.
“Grace and Jack’s contributions are a source of tremendous pride,” said Shuo Zhang, assistant professor in MSU’s Department of Physics and Astronomy. “Their work exemplifies MSU’s commitment to cutting-edge research and fostering the next generation of astronomers. This research is a prime example of how MSU scientists are unlocking the secrets of the universe, bringing us closer to understanding the nature of black holes and the dynamic environment at their heart. of our galaxy.”
Understanding black hole outbursts
The newly discovered flares are dramatic bursts of high-energy light that occur when the black hole picks up material, such as gas clouds or stars. These outbursts provide valuable data about the physical conditions near the event horizon, the boundary beyond which nothing can escape the black hole’s gravity. When a black hole consumes matter, the material is heated to extreme temperatures as it accelerates and spirals inward, emitting intense X-rays and other radiation. This radiation is what scientists observe as bursts.
Torches are usually short and last from a few minutes to a few hours, but can release a tremendous amount of energy during that time. The energy output of these solar flares can be equal to that of millions of suns. Sanger-Johnson’s analysis, which sifted through data from 2015 to 2024, revealed the characteristics of these flares, building a comprehensive database for future research. Every flame provides a snapshot of the dynamical processes taking place near the black hole and offers clues about the behavior of the accreting material and the physics of the extreme environment.
“We hope that by building this database of Sgr A* flares, we and other astronomers can analyze the properties of these X-ray flares and infer the physical conditions in the extreme environment of the supermassive black hole,” says Sanger-Johnson. said. By studying the timing, intensity and frequency of these outbursts, researchers can deduce details about the rate at which the black hole consumes material and the nature of the surrounding accretion disk. This information is crucial for developing models for black hole growth and activity.
