Cosmos: Giant gas bubble discovered near the Milky Way

A similar structure in the northern sky, the so-called north polar spur, was described as early as the 1980s. Previously it was suspected that it could have come from a nearby supernova explosion. Taken together, the north and south structures now show that the cause is more likely to be in the center of the galaxy, researchers report in the journal „Nature“. The shape of the two gas bubbles is reminiscent of an hourglass below and above the galactic disk.

“The most likely explanation for these enormous structures is that a few tens of millions of years ago an unbelievable amount of energy was ejected from the galactic center into the hot gas envelope around our galaxy, which triggered a rapid, large shock wave,” says eRosita project manager Thomas Mernik. “Which event is behind this is not yet fully understood. It may be an eruption of the black hole around which our Milky Way orbits.”

Mapping of the sky

“Thanks to its sensitivity as well as energy and angular resolution,” eRosita “can map the entire X-ray sky at a previously unattainable depth and thus clearly identify the southern bubble,” says Michael Freyberg from the Max Planck Institute for Extraterrestrial Physics. The X-ray telescope scans the entire sky every six months. The data enables the scientists to search for large-scale structures.

A Russian launch vehicle with “eRosita” and a Russian telescope on board was launched into space from the Baikonur spaceport in Kazakhstan in July 2019. The telescope has been sending data ever since. This results in sky maps that depict the universe and its development.

The astronomers assume that with “eRosita” they will find around 100,000 galaxy clusters and several million active black holes in the centers of the galaxies. Because light from distant galaxies travels a long time, the telescope can look back up to six billion years.

–

–