Researchers studying 3D maps of the universe and have discovered one of the biggest cosmic structures ever. The structure is a vast wall that stretches 1.4 billion light-years across and contains hundreds of thousands of galaxies. It has been dubbed the South Pole Wall and has been hiding in plain sight.
Scientists say that it has remained undetected until now because large parts of it sit half a billion light-years away behind the bright Milky Way galaxy. The South Pole Wall rivals the Sloan Great Wall in size. The latter is the sixth-largest cosmic structure ever discovered. Astronomers have long known that galaxies are not randomly dispersed throughout the universe, but are clumped in what is known as the cosmic web.
The cosmic web consists of strands of hydrogen gas where galaxies are strung like pearls on a necklace surrounding large empty voids. Scientists are working on mapping the intergalactic threads as part of a field called cosmography.
Previous work in the field has charted other massive galactic structures. The single largest structure ever discovered is called the Hercules-Corona Borealis Great Wall and spans 10 billion light-years. To create their new map, the researchers used new sky surveys to peer into a region called the Zone of Galactic Obscuration.
That is an area of the southern part of the sky where the bright light of the Milky Way blocks most of what’s behind it. The team used a method that includes the commonly used redshift but also takes into account the motions of galaxies around each other. The advantage of that technique is that it allows scientists to detect hidden mass that gravitationally influences how other galaxies move.