According to Einstein, nothing travels faster than light, and if something does reach 30 percent of the speed of light, then unimaginable forces must exist for such an acceleration - such as near Sagittarius A*, the supermassive black hole at the center of our galaxy.
With the help of the Chilean ALMA observatory, astronomers have now observed a hot clump of gas that orbits the center of our galaxy at a distance of five times the Schwarzschild radius within just 70 minutes - i.e. with an orbital radius of around 60 million kilometers, which roughly corresponds to that of Mercury.
Sibylle Anderl
Editor in the feuilleton, responsible for the "Nature and Science" department.
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The researchers led by Maciek Wielgus from the Max Planck Institute for Radio Astronomy in Bonn have now presented these results in "Astronomy & Astrophysics".
The Event Horizon Telescope (EHT), a global network of eight radio observatories, only published the first image of Sagittarius A* this spring.
As part of these observations, the ALMA data that have now been evaluated were also recorded in 2017.
Coincidentally, some of the observations took place shortly after a burst of X-ray waves was detected in the Galactic Center.
Such outbursts are attributed to bubbles of hot gas circling the black hole rapidly and in close proximity.
The ALMA observations now provide evidence for the first time of such an event at radio wavelengths - and also that the burst of radiation has a magnetic origin.
Namely, the millimeter data contain information about the magnetic field of Sagittarius A* in the form of the vibration direction of the received radiation.
Using a dynamic emission model, the movement of the gas bubble and even properties of the black hole and its surroundings could be reconstructed from the observations.
According to this, there is evidence of a positive angular momentum of the black hole and of a clockwise rotating disc structure in which the magnetic field prevents the gas swirling into the black hole from moving in such a way that bubbles and streams form.
The astronomers now expect further insights from the comparison with observations in the infrared, in particular with the GRAVITY instrument of the Max Planck Institute for Extraterrestrial Physics installed at ESO's Very Large Telescope Interferometer (VLTI) in Chile.
Gas bubbles, initially visible in the infrared, could become observable at radio wavelengths once they have cooled sufficiently.
According to the authors, in order to relate the data recorded at different wavelengths to one another, such observations would have to be carried out simultaneously in a targeted manner in the future.