Complex structures around the galactic core were discovered in 2019 by the XMM-Newton and Chandra space telescopes, creating the first highly detailed X-ray map of the central region of our Galaxy.
The center of our Galaxy hosts a supermassive black hole with relatively weak emissivity, but it may have been much more active in the past. X-ray and gamma-ray observations have revealed two enormous structures known as “Fermi Bubbles” located above and below the galactic plane, as shown in the figure. These bubbles are filled with highly energetic particles moving at nearly the speed of light, which were released from the galactic center a few million years ago. X-ray observations reveal structures resembling “chimneys” that connect the region around the galactic center to the Fermi Bubbles. These structures were discovered in 2019 after more than 750 hours of X-ray observations using the “XMM-Newton” and “Chandra” space telescopes, creating the first highly detailed X-ray map of the central region of our Galaxy.
This discovery could reveal how energy is transported from the central regions of the galaxy to the outer Fermi Bubbles. In particular, it appears that this could actually happen through these “chimneys,” whose morphology suggests they might be channels carved out by powerful jets from supernovae near the galactic center. The energy from these jets could then, by passing through these galactic chimneys, fuel and inflate the Fermi Bubbles. However, a similar effect could also be the result of extremely energetic explosions produced by the accumulation of plasma following the gravitational shredding of stars that come too close to the black hole. However, it is still not possible to determine which of these two hypotheses is correct.
There are still many open questions. At the moment, only a part of the region at the base of the Fermi Bubbles has been observed. Future observations of this entire region will undoubtedly help clarify the nature of the X-ray emissions from the chimneys and the various phenomena occurring within the restless heart of the Milky Way.
References:
Ponti, G., Hofmann, F., Churazov, E. et al. An X-ray chimney extending hundreds of parsecs above and below the Galactic Centre. Nature 567, 347–350 (2019). https://doi.org/10.1038/s41586-019-1009-6
