The intergalactic medium unveiled: Cosmic Web Imager directly observes 'dim matter'

(Phys.org) --Caltech astronomers have taken unprecedented images of the intergalactic medium (IGM)--the diffuse gas that connects galaxies throughout the universe--with the Cosmic Web Imager, an instrument designed and built at Caltech. Until now, the structure of the IGM has mostly been a matter for theoretical speculation. However, with observations from the Cosmic Web Imager, deployed on the Hale 200-inch telescope at Palomar Observatory, astronomers are obtaining our first three-dimensional ...