It may have been active for 200 years

The black hole at the center of the Milky Way is sleeping, but it wasn’t always that way. A new study shows that Sagittarius A* was last active about 200 years ago.

STRASBOURG – The supermassive black hole at the center of our Milky Way galaxy known as Sagittarius A* (Sgr A*) has been asleep for a long time and has not accumulated any material from its surroundings for a long time. This discovery comes from scientific research because the black hole is much weaker compared to other black holes in the centers of galaxies that can be observed from Earth. However, a recent study reveals that the sleeping giant Sagittarius A* woke up about 200 years ago – not long ago on cosmic time scales – to gorge on gas and other cosmic matter around it.

To make this groundbreaking discovery, the In the famous magazine nature published A team of researchers led by astronomer Frédéric Marin of the Observatoire de Strasbourg used the NASA IXPE Space Telescope. This telescope allows accurate measurements of the direction and intensity of the electric field of light waves and was directed at the huge gas clouds in the immediate vicinity of the black hole. Previous studies have revealed strikingly bright X-ray signatures there, even though it should normally be dark and cold.

The Sagittarius A* black hole was not calm

“One scenario as to why these giant molecular clouds glow is that they are actually echoes of X-ray flashes long gone, indicating that our supermassive black hole wasn’t very quiet just a few centuries ago,” explains lead author Marin in one. NASA ad.

To perform a comprehensive X-ray analysis, the research team combined data from the IXPE telescope with data from the Chandra and XMM-Newton space telescopes. Through this combination, they were able to isolate the X-ray signal and pinpoint its exact point of origin. “The polarization angle acts like a compass, pointing the way to a mysterious, elusive light source. And what lies in that direction? Nothing less than Sgr A*.”

The black hole Sagittarius A* was awake at the beginning of the 19th century

In the course of the research, the team found that the X-rays emitted by the giant molecular clouds were actually reflecting light from the intense, short glow that originated either within the black hole itself or in its immediate vicinity. It is believed that this phenomenon occurred when a black hole suddenly sucked in a large amount of matter. Based on the available data, the research team concluded that the supermassive black hole at the center of the Milky Way became active for a short period of time about 200 years ago, that is, at the beginning of the nineteenth century.

Next, the researchers plan to repeat the observation and make more precise measurements. With additional data, they can, for example, make more accurate estimates of when the black hole erupted and how strong the activity was. This kind of study will help scientists gain new insights into the physical processes required to awaken Sgr A* from its sleep, explains IXPE scientist Stephen Eilert. By better understanding the physical processes, they can understand how to wake the sleeping supermassive black hole.

“We know that active galaxies and supermassive black holes can change on the human time scale,” Eilert confirms. “We are learning more about this galaxy’s behavior over time, its history of explosions, and we look forward to continuing to monitor it to identify changes that are typical and unique.”

Machine assistance was used in this editorial article. The article was carefully screened by editor Tanya Banner before it was published.