Scientists discover huge ‘extragalactic structure’ behind the Milky Way
Astronomers have discovered a huge extragalactic structure that lies far behind the Milky Way‘s center.
Known as the Avoidance Zone, this phantom region is an empty spot on our map of the universe, covering anywhere from 10% to 20% of the night sky. The reason we can’t see it — at least with standard visible-light telescopes — is because the Milky Way’s bulging center blocks our view of it; the center of our galaxy is so dense with stars, dust and others matter that light from the avoidance zone is scattered or absorbed before it reaches Earth’s telescopes.
However, researchers have had better luck discovering the zone’s secrets with telescopes that can detect Infrared radiation – a kind of energy invisible to human eyes, but powerful enough to shine through dense clouds of gas and dust. Infrared surveys of the Avoidance Zone have found clues to thousands of individual galaxies shining through the cosmic fog, though little is known about the large-scale structures lurking there.
Now, researchers have combined data from several of those infrared surveys to reveal the most colossal structure ever detected in the avoidance zone, according to a study published Oct. 28 in the preprint database. arXiv.org. (This study has not yet been peer-reviewed, although it has been submitted to the journal Astronomy and Astrophysics for review).
The mysterious structure, located about 3 billion light-years from Earth, appears to be a large cluster of galaxies contracted by a shared center of gravity. Using observations from the VVV Survey – a study that studies the Milky Way’s central bulge at infrared wavelengths using the Visible and Infrared Survey Telescope for Astronomy in Chile – the study authors found evidence of at least 58 galaxies clustered together. were in a small piece of the zone of avoidance.
Clusters of galaxies are the largest gravitationally bound objects in the universe; the largest known clusters contain hundreds of thousands of galaxies clustered together. Unfortunately, it’s impossible to say how wide or massive the newly discovered cluster is, given the vast distances and numerous obstacles between the cluster’s stars and Earth.
However, the mere detection of this colossal object shows that the avoidance zone may not be as inscrutable as once thought. Future infrared studies – including possible observations by the James Webb Space Telescopewho has already used his infrared camera to deepest view of the universe so far – should further help scientists unravel the hidden secrets behind the Milky Way’s bulge.
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