Magnetic Blob Orbiting Earth's Closest Supermassive Black Hole Shoots Radiation Toward Us Every 76 Minutes

At the center of our galaxy, the Milky Way, there is a supermassive black hole. We call it Sagittarius A* and it weighs the equivalent of 4.3 million Suns. It is orbited by a bunch of stars with a period of years or longer. New evidence suggests that there is something else orbiting it much faster: A magnetized blob of material moving at incredible speed.

The latest evidence comes from a yet-to-be-peer-reviewed analysis of gamma-ray emission. The data is publicly available and it was used by researchers at the National Autonomous University of Mexico to create a timeline of emission from June 2022 to December 2022. The data is from NASA's Fermi Gamma-ray Space Telescope. The team found a repeating emission, appearing every 76.32 minutes.

The light curve shows the repeating pattern clearly, and the period is consistent with observations from last year in a completely different wavelength. Radio observations also suggested that something is going around Sagittarius A* about every 74 minutes, with an uncertainty of 6 minutes higher or lower.

Sagittarius A*’s radius is 12 million kilometers (7.4 miles) and this object is expected to be fairly close to it, five times the black hole radius. To cover the orbital distance in just over an hour, the blob needs to travel at 30 percent of the speed of light, truly an impressive velocity.

But the radio and gamma-ray emissions are not the only ones recorded. There is also x-ray emission from around the black holes but that repeats every 149 minutes, about twice as long as the gamma and radio emission. The researchers believe that the two are connected.

"The coincidence of the multiwavelength periodicity in X-ray and gamma-ray points towards a single physical mechanism that produces it," the team wrote in the paper.

The blob is believed to be magnetized, providing insights into the magnetic field around the supermassive black hole. While Sagittarius A* is not actively feeding like other supermassive black holes, it still has a disk of material around it – and the blob's emission tells us that it goes around it clockwise.

Studying future flares across the range of wavelengths beyond the visible spectrum will allow a better understanding of the environment around our friendly neighborhood supermassive black hole.

The paper is available in the online paper repository ArXiv .