The Milky Way just burped out a fiery bubble of plasma

Date:15 December 2020

Astronomers just spotted a massive cosmic burp coming from the center of our galaxy. The fiery bubble of plasma is expanding more than 45,000 light-years below the Milky Way Galaxy and emitting high-energy X-rays.

Scientists have known of a similar X-ray bubble expanding from the top of the galaxy for many years, but the bottom half was previously invisible to less-sensitive X-ray telescopes.

The origin of the bubbles remains a mystery. Researchers believe these new observations may shed some light on what caused the galactic belch. Whatever it might have been, it was certainly epic; the structures span more than half of the visible sky.

“Because it was only one-sided, people had a lot of trouble figuring out what they were and where they come from,” Andrea Merloni told New Scientist. “Now we finally see the southern bubble, so a lot of the controversy about the northern bubble is resolved.”

The astronomers observed the balloons of charged particles using the eROSITA X-ray telescope aboard the Russian-German Spektr-RG space observatory. eROSITA scans the entire sky twice a year, creating an all-sky survey of X-ray radiation. When the telescope isn’t searching for enormous galactic burps, it’s mapping out the large-scale structure and expansion of the universe to better understand dark energy.

Both hourglass-shaped bubbles show an uncanny resemblance to the Fermi bubbles discovered by NASA’s Fermi Gamma-ray Space Telescope a decade ago, but are larger and more energetic. The Fermi bubbles are believed to be the remnant of an extraordinary eruption from the supermassive black hole at the center of the galaxy, millions of years ago.

Astronomers have observed supermassive black holes in other galaxies belching out colossal high-energy jets after ingesting large amounts of matter. Other scientists believe a burst of star formation could also cause such an outburst, since astronomers have witnessed starbursts in other galaxies driving enormous gas outflows.

What surprised Merloni and her colleagues was the apparent sharpness of the boundaries of the bubbles they observed. This suggests the bubbles were created from violent shocks caused by a massive injection of energy from the center of our galaxy, Merloni explained.

These findings could help scientists understand how galaxies recycle their mass and evolve over time. The stars, gas, and dust that astronomers see with optical telescopes make up less than 10 percent the mass of the galaxy.

Astronomers believe considerable amounts of matter are hidden away in the dim outskirts of galaxies. At the very least, the discovery shows there’s a lot more to our galaxy than meets the eye.

This article was written by Tim Childers and published to Popular Mechanics on 11 December 2020.

Picture: Pixabay

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