(ORDO NEWS) — In 2020, the eROSITA X-ray telescope captured images of two huge bubbles extending far above and below the center of our galaxy. Now scientists have revealed their nature.
For two years, astrophysicists have been trying to figure out the nature of these bubbles. Now it has become clear that they are released by a black hole in the center of our Milky Way.
Called Fermi bubbles and eROSITA, these two formations have a total length of about 11 kiloparsecs. One parsec is equivalent to 3.26 light years, or about three times the distance light travels in a year. Thus, the length of these two bubbles is almost 36,000 light years.
For comparison, the Milky Way galaxy has a diameter of 30 kiloparsecs, and our solar system is about 8 kiloparsecs from the center of the galaxy. The eROSITA-detected formations are roughly twice the size of Fermi bubbles and expand under the action of a shock wave emanating from the center of galaxies, the researchers said .
The nature of bubbles in the center of the Milky Way
There are two competing models that explain Fermi bubbles and eROSITA, named after the telescopes that discovered them.
The first suggests that the formations occurred as a result of a supernova explosion, in which a star ejects material at the end of its life. The second model, supported by the team’s findings, suggests that these bubbles are caused by energy ejected from a supermassive black hole at the center of our galaxy.
These jets from black holes are created when material moves towards a black hole but never crosses its event horizon, a mathematical surface after which the gravity of a celestial body no longer allows the object to escape outward.
But the gas orbiting around the hole can be expelled outward in what looks like a gravitational maneuver. Because this material is blasted back into space, black holes don’t grow out of control. But the energy ejected from the black hole shifts material near it, creating these bubbles.
They have cosmic rays inside them, a form of high-energy radiation. The eROSITA bubbles contain Fermi bubbles whose contents are unknown. But the researchers’ models can predict the intensity of cosmic rays inside each of the structures.
The sloshing of energy from a black hole inflates the bubbles, and the energy itself can be in the form of kinetic, thermal, or ‘cosmic radiation’ energy. Of these forms of energy, the Fermi mission has so far been able to detect only gamma rays from cosmic rays.
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