This supercomputer simulation shows part of the cosmic web 11.5 billion years ago. The cube is 24 million light years in length, width and depth. Image credit: J. Onorbe/MPIA
Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the “normal” matter in the Universe. New results from NASA’s Chandra X-ray Observatory may have helped them locate this elusive expanse of missing matter.
From independent, well-established observations, scientists have confidently calculated how much normal matter — meaning hydrogen, helium and other elements — existed just after the Big Bang. In the time between the first few minutes and the first billion years or so, much of the normal matter made its way into cosmic dust, gas and objects such as stars and planets that telescopes can see in the present-day Universe.
The problem is that when astronomers add up the mass of all the normal matter in the present-day Universe about a third of it can’t be found. (This missing matter is distinct from the still-mysterious dark matter.)
One idea is that the missing mass gathered into gigantic strands or filaments of warm (temperature less than 100,000 Kelvin) and hot ...