Mar 27 2019
It is believed that energy and matter flowing from the core of a galaxy have an important role to play in the creation and development of various structures in the universe, including the solar systems.
Looking into the heart of the galaxy: this false-cooler image shows the X-ray emissions from the central region of the Milky Way. The colors are a measure of how energetic the X-rays are. North and south of the galactic plane, you can clearly make out long, coherent structures—the chimneys. These form a link between the inner region around the supermassive black hole Sagittarius A* and the Fermi bubbles much further out. Point sources and very bright areas have been removed from the image. (Image credit: MPE)
Astronomers, headed by the Max Planck Institute for Extraterrestrial Physics in Garching, have now identified two broad chimneys of gas in X-ray images. These chimneys link the inner areas of the Milky Way south and north of the galactic plane with structures that are much further out.
The Milky Way is a relatively tranquil galaxy, and it is very rare to see huge outbursts of energy from its core. However, years ago, astronomers discovered bipolar protuberances near the Galactic Centre, which is recognized by the radio source Sagittarius A*. These lobes or wings can be observed on the radio as well as X-ray spectral areas. They demonstrate outflows from the center and extend only to distances of about 50 light years.
The two Fermi bubbles appear much further out from the center and these were also detected some time ago. They are capable of tracing the radiation from relativistic particles as visible in gamma light, and also extend much beyond the galactic plane by around 25,000 light years. Hence, in the past, huge amounts of energy must have been obviously released in the Milky Way
Both the prominent X-ray structures, called “chimneys,” detected by the astronomers seem to connect the lobes in the internal areas of the Galactic Center with the two Fermi bubbles.
A few years ago, we discovered an overdense region of hot plasma directly above the Galactic Centre based on X-ray observations. For that reason, we wanted to scan a far larger region using the European X-ray satellite XMM-Newton.
Gabriele Ponti, Study Lead Author and Former Researcher, Max Planck Institute
The study has been reported in the journal, Nature.
Armed with their latest measurements, the researchers, in fact, succeeded in unmistakably proving the existence of this hot plasma, and they also established its composition and shape. In addition, the team identified the chimneys, stretching hundreds of light years south and north of the Galactic Center. According to the scientists, this clearly indicates that both the two structures should exhibit a common origin.
Probably, they are made of gas produced in a rapid and cold stream on either side of the galactic plane, and also perpendicular to the galactic plane. This outflow can possibly arise either from supernova explosions in the central star cluster or from stars split apart by the gigantic black hole at the core of the Milky Way. This kind of events may constantly blow mass and energy out of the Galactic Center. and transmit them to the Fermi bubbles.
The chimneys are approximately cylindrical in shape and have sharp vertical boundaries. They’re most likely contained by magnetic pressure.
Dr Florian Hofmann, Postdoctoral Researcher, Max Planck Institute for Extraterrestrial Physics, Garching
Furthermore, both the chimneys are not stringently symmetrical: “That’s presumably a consequence of galactic weather—essentially, an interplay with local clouds in the interstellar medium,” Hofmann stated.
Eugene Churazov from the Max Planck Institute for Astrophysics informed that the Fermi bubbles are reminiscent of structures created by highly energetic outflows from the supermassive black holes in galaxy clusters.
On the other hand, the appearance of the chimneys also leaves open the possibility that less energetic processes are involved.
Dr Eugene Churazov, Scientific Staff, Max Planck Institute for Astrophysics
The scientists are still mystified over the mechanism through which both the two recently identified chimneys were created—and whether they are actually a continuation of the internal lobes. Nevertheless, they provide a better understanding of how activity in the center of the Milky Way correlates with macroscopic structures at the galactic level and how it may well affect even the creation and development of the Milky Way.