NASA visualization of the Milky Ways Fermi bubbles. Credit: ESA/Gaia/DPAC
Evidence shows strong outflowing winds responsible for the “Fermi bubbles.”
A scientist from Tokyo Metropolitan University has actually revealed that large gamma-ray giving off bubbles around the center of our galaxy were produced by fast-blowing outward winds and the associated “reverse shock.” Numerical simulations effectively replicated the temperature profile observed by an X-ray telescope. Such outflows have actually been observed in other galaxies; this finding recommends similar winds may have been blowing in our own galaxy till rather recently.
One of these is the “Fermi bubbles,” so-called due to the fact that they were first discovered by the Fermi Gamma-ray Space Telescope in 2010. These bubbles are enormous gamma-ray discharging areas that extend either side of the center of our galaxy over roughly 50,000 light-years, extending out from the airplane of the galaxy like balloons as shown in the figure.
Fast winds draining from the stellar center develops a forward shock and a reverse shock. The latter forms the overview of the Fermi bubbles. Credit: Tokyo Metropolitan University
Now, Professor Yutaka Fujita from Tokyo Metropolitan University has actually provided theoretical proof showing how such items might have been formed. Since their discovery, lots of hypotheses have actually been advanced about the development of the Fermi bubbles, including an explosive activity of the main supermassive black hole, winds from the great void, and consistent star formation activity. Telling these scenarios apart is a tough job, however the availability of cutting edge X-ray observations from the Suzaku satellite provides us a chance to compare measurements with what we get out of numerous situations.
The simulations of Professor Fujita thought about fast outflowing winds from the great void injecting the required energy into the gas surrounding the center of the galaxy. Comparing with the measured profiles, they found that there was a likelihood that the Fermi bubbles are produced by the fast outflowing winds, blowing at 1000km per second over 10 million years. These are not winds as we would experience them on earth, but streams of extremely charged particles taking a trip at high speeds and propagating through area. These winds travel outwards and connect with surrounding “halo gas,” causing a “reverse shock” that develops a characteristic temperature level peak. The Fermi bubbles correspond to the volume on the within of this reverse shock front. Significantly, simulations also revealed that an instantaneous surge at the center could not reproduce the profiles measured by the telescope, lending weight to a circumstance based on steady winds created by the main great void.
The author notes that the winds predicted by the simulation are similar to outflows observed in other galaxies. The correspondence recommends the same sort of enormous outflows seen in other parts of the universe existed in our own galaxy until relatively recently.
Recommendation: “Evidence for effective winds and the associated reverse shock as the origin of the Fermi bubbles” by Yutaka Fujita, 12 November 2022, Monthly Notices of the Royal Astronomical Society.DOI: 10.1093/ mnras/stac3312.
This work was supported by JSPS KAKENHI Grants-in-Aid (Grant Numbers 20H00181, 22H00158, and 22H01268).
One of these is the “Fermi bubbles,” so-called because they were first discovered by the Fermi Gamma-ray Space Telescope in 2010. Since their discovery, numerous hypotheses have actually been put forward about the formation of the Fermi bubbles, consisting of an explosive activity of the main supermassive black hole, winds from the black hole, and steady star formation activity. Comparing with the measured profiles, they found that there was an excellent opportunity that the Fermi bubbles are produced by the fast outflowing winds, blowing at 1000km per second over 10 million years. The Fermi bubbles correspond to the volume on the within of this reverse shock front.