Japanese scientist explains how Fermi bubbles formed
(ORDO NEWS) — A scientist at Tokyo Metropolitan University has shown that the large bubbles around the center of the Milky Way were formed by fast, outward blowing winds and an associated back shock wave.
The simulation successfully reproduced the temperature profile observed by the X-ray telescope. Such flows have also been observed in other galaxies.
This discovery suggests that similar winds may have blown in our galaxy until very recently.
Fermi bubbles were discovered by the Fermi Gamma Ray Space Telescope in 2010.
They are huge gamma-ray emitting regions that extend on either side of the center of the Milky Way for about 50,000 light-years, protruding from the plane of the galaxy like balloons.
Despite their mind-boggling scale, the mechanism by which they form has yet to be deciphered.
Professor Yutaka Fujita of Tokyo Metropolitan University presented theoretical evidence demonstrating how such objects could form.
Since the discovery of bubbles, many hypotheses have been put forward about their formation, including the explosive activity of a central supermassive black hole, black hole winds, and sustained star formation.
The availability of state-of-the-art X-ray observations from the Suzaku satellite makes it possible to compare measurements with what astronomers expect to receive under various scenarios.
Professor Fujita’s simulations took into account the fast winds emanating from the black hole, injecting the necessary energy into the gas surrounding the center of the galaxy.
Fujita concluded that Fermi bubbles could be formed by fast outward winds blowing at 1,000 km per second for 10 million years.
These are not our terrestrial winds, but streams of highly charged particles moving at great speed and propagating in space.
These winds move outward and interact with the gas around the halo, causing a back shock wave that creates a characteristic temperature peak.
The Fermi bubbles correspond to the volume inside this backward shock wave front.
The simulations also showed that the instantaneous explosion at the center could not reproduce the profiles measured by the telescope, lending weight to a scenario based on steady winds generated by the central black hole.
The author notes that the winds predicted by the simulation are similar to those observed in other galaxies.
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