Our small part of the universe is contained within a vast shell of dark matter.
It’s a space between a few The isolated stars dotted throughout this nearly invisible sphere may seem empty, but there’s a lot going on in the Milky Way’s wilderness.
By studying the hot gas glowing in space around galaxies, astrophysicists have found evidence of a huge magnetic field wrapped in and around galaxies’ dark matter halos.
“This study provides the first detailed measurements of the X-ray magnetic field of the halo-emitting Milky Way galaxy and reveals a new connection between star-forming activity and galactic outflow,” said National Astronomical Physics. Zhang Heshou, an astrophysicist at the Institute for Scientific Research (INAF), explains. In Italy.
“Our findings show that the magnetic ridges we observed are not just a chance structure, but are closely associated with the star-forming regions of our galaxy.”
The study was conducted on X-ray light emitted by two giant structures that span above and below the surface of the Milky Way. Discovered in 2020, these “eROSITA bubbles” extend over 45,000 light years on either side of the galactic center. They are powered by massive outflows of gas and plasma. When this medium is shocked, the bubbles glow brightly in the X-ray range.
When the bubbles were discovered, scientists thought there were two main candidates for the source.
One is the activity from the supermassive black hole at the center of the Milky Way. If the jet has gone through a period of activity, the heat and energy generated may have blown the bubbles away.
The second explanation is starburst activity. Although the galaxy is currently fairly quiet, it may have had a period of intense star formation. This, too, could have generated enough heat and energy to create an eROSITA bubble that expanded into the galaxy’s halo.
Zhang and his colleagues thought that if magnetic fields existed, they might have some answers.
When light passes through a magnetic field, it is oriented according to the direction of the magnetic field, called polarization. When we examine light collected by a telescope, we can see evidence of its polarization as well as the direction of the magnetic field that produced it.
When researchers studied the broad polarization of light emitted by the eROSITA bubble, they discovered giant, long magnetized filaments. If we could see these filaments with our own eyes, they would stretch across the sky up to 150 times the width of the full moon, researchers say.
And the filaments suggest that the origin of eROSITA bubbles is star formation. Star-forming rings located about 10,000 to 16,000 light-years from the galaxy’s center may generate heat and winds that send hot gas and plasma flowing tens of thousands of light into the galaxy’s halo. There is sex. – It’s been going on for years.
“We now know that a small number of ‘active’ galaxies can trigger outflows of material accelerated by accretion onto supermassive black holes or intense star formation events, which can severely impact their host galaxies.” It is well known that such outflows are thought to be a fundamental component of galaxies, controlling the growth of galaxies and their central black holes, said INAF astrophysicist Gabriele.・Ponti explains.
“What I find interesting about this case is that even the Milky Way, a stationary galaxy like many other galaxies, can cause strong outflows, especially when the star-forming rings at the edge of the spinning center of the galaxy “Perhaps the Milky Way can reveal to us phenomena common to galaxies similar to our own and help us elucidate the growth and evolution of these objects.” I guess it is. ”
Of course, that’s not certain. More analysis will be needed to definitively determine the cause of the bubbles. The team’s findings are consistent with recent simulations, but more detailed simulations will be needed to determine whether star formation causes outflows like those observed in eROSITA bubbles.
But magnetic fields represent an important piece of the puzzle.
“This study breaks new ground in our understanding of galactic halos and will contribute to deepening our knowledge of the Milky Way’s complex and dynamic star-forming ecosystem,” said Professor Zhang.
This research natural astronomy.
