Bubbles of the Andromeda Nebula

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Russian astronomers have discovered gigantic gamma-ray regions in the Andromeda Nebula, similar to the "Fermi bubbles" in our Galaxy.

In 2010, when analyzing data collected by the Fermi Space Telescope (NASA), astronomers at the Harvard-Smithsonian Astrophysical Center discovered giant formations that emit gamma rays in our Galaxy. Outwardly, they look like two huge bubbles located on either side of the plane of the Milky Way disk, and are called "Fermi bubbles". Each bubble is about 25,000 light-years across (recall that the Milky Way is about 100,000 light-years in diameter) and is estimated to be 2.5 to 4 million years old. The walls of the bubbles emit in the X-ray range.

The origin of these formations has not been unequivocally established, although several hypotheses have been put forward. Astrophysicists call a starburst or cataclysm associated with a supermassive black hole in the center of the galaxy, the interaction of cosmic rays with the matter surrounding the visible disk of the galaxy (galactic halo) and its magnetic field as possible mechanisms for the appearance of Fermi bubbles. In particular, the bubbles could be generated by the collision of high-energy plasma flows from the black hole (jets) with the matter surrounding the galaxy.

The existence of Fermi bubbles in our Galaxy leads to a natural assumption about the possible existence of similar structures in other galaxies. Moreover, this is evidenced by some observations in other ranges. An obvious target for their search is the Andromeda Nebula (M31). Not only is it the largest galaxy in the local group and also the closest large galaxy to Earth, it has the same spiral shape as the Milky Way.

Maxim Pshirkov and Konstantin Postnov from the State Astronomical Institute. Sternberg Moscow State University together with Valery Vasiliev, representing the Institute of Astronomy of the Society. Max Planck, using observational data from the Fermi telescope for all seven years of its existence (it was launched in 2008), they searched for gamma-ray regions around the Andromeda Nebula and came to the conclusion that a structure similar to the "Fermi bubbles" in our The galaxy. Its dimensions are also about 21-25 thousand light, and the brightness is even higher, which is easily explained by the presence of a more massive black hole in the center of Andromeda. Analyzing the features of the structure and emission of bubbles, astrophysicists came to the conclusion that their origin does not correspond to the annihilation of dark matter and the interaction of cosmic rays with matter. Most likely, the activity of the central supermassive black hole or a burst of star formation is "to blame" for their formation. The astronomers published the results of their work in the Oxford journal Monthly Notices of the Royal Astronomical Society.

It should be noted that the search for gamma radiation from such formations is an extremely difficult task, since it is masked by background gamma radiation coming from all directions, which arises from the interaction of cosmic ray particles with interstellar gas. According to available estimates, the emission from the halo of our Galaxy is only about 10% of the extragalactic one. Therefore, the search for bubbles in other galaxies requires the development of very careful mathematical algorithms for clearing the signal from background noise.

In addition, astrophysicists have suggested that Fermi bubbles exist in all spiral galaxies, but future observations will bring final clarity to this issue.