THE INTERGALACTIC MEDIUM UNVEILED:
Cosmic Web Imager directly observes Dim Matter
PhysOrg News
A few words about INTERGALACTIC SPACEÂ
THE VOIDSÂ [Wikipedia]
The vast empty spaces between filaments (the largest-scale structures in the Universe), which contain very few, or no, galaxies are called the voids Â
IGM — THE INTERGALACTIC MEDIUM [Wikipedia]
Surrounding and stretching between galaxies, there is a diffuse gas that is organized in a galactic filamentary structure. This material is called the intergalactic medium.
The density of the IGM is 5-200 times the average density of the Universe.
It consists mostly of ionized hydrogen; i.e. a plasma consisting of equal numbers of electrons and protons.
As gas falls into the intergalactic medium from the voids, it heats up to temperatures of 105 K to 107 K and is called the warm–hot intergalactic medium (WHIM). (Although the gas is very hot by terrestrial standards, 105 K is often called "warm" in astrophysics.)
Computer simulations and observations indicate that up to half of the atomic matter in the Universe might exist in this warm-hot, rarefied state.
Until now, the structure of the IGM has mostly been a matter for theoretical speculation. However, with observations from the Cosmic Web Imager, an instrument designed and built at Caltech and deployed on the Hale 200-inch telescope at Palomar Observatory, astronomers are obtaining our first three-dimensional pictures of the IGM.
The Cosmic Web Imager has already detected one possible spiral-galaxy-in-the-making that is three times the size of our Milky Way.
IMAGES  [1] Comparison of the Lyman alpha blob observed with the Cosmic Web Imager and a simulation of the cosmic web based on theoretical predictions. Credit: Christopher Martin, Robert Hurt  [2] Observation of quasar (QSO 1549+19) taken with Cosmic Web Imager. Blue shows hydrogen gas surrounding and inflowing to quasar. Credit: Christopher Martin, Robert Hurt
