Astronomers using NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton detected a vast reservoir of gas lying along a wall-shaped structure of galaxies about 400 million light years from Earth.
In the image above the spiral and elliptical galaxies are shown in the Sculptor Wall along with the newly detected intergalactic gas, part of the so-called Warm Hot Intergalactic Medium (WHIM), shown in blue.
This discovery is the strongest evidence yet that the “missing matter” in the nearby Universe is located in an enormous web of hot, diffuse gas.
The X-ray emission from WHIM in this wall is too faint to be detected, so instead a search was made for absorption of light from a bright background source by the WHIM, using deep observations with Chandra and XMM. This background source is a rapidly growing supermassive black hole located far beyond the wall at a distance of about two billion light years. This is shown in the illustration as a star-like source, with light traveling through the Sculptor Wall towards the Earth. The relative location of the background source, the Sculptor Wall, and the Milky Way galaxy are shown in a separate plot, where the view instead looks down on the source and the Wall from above.
The wall is faint beyond 500 million light years because the data is incomplete beyond that distance. The nearest part of the wall (the Phoenix supercluster) lies next to a large rectangular void, the Sculptor Void – one of the largest voids in the nearby universe.
One Million Galaxies
A plot of over one million of the brightest “extended sources” detected by the Two Micron All Sky Survey (2MASS) shows that they are not. The vast majority of these infrared extended sources are galaxies. Visible above is an incredible tapestry of structure that provides limits on how the universe formed and evolved. Many galaxies are gravitationally bound together to form clusters, which themselves are loosely bound into superclusters, which in turn are sometimes seen to align over even larger scale structures. In contrast, very bright stars inside our own Milky Way Galaxy cause the vertical blue sash.
“Atlas Image [or Atlas Image mosaic] obtained as part of the Two Micron All Sky Survey (2MASS), a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.”
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