The case of the disappearing gas

The gaseous matter between clusters of galaxies collides, producing strong x-rays, and this results in cooling of the gases. The cool gas condenses into cold gas clouds, which condenses further to form stars. Observations show that the amount of cool mass does not match the rate of cooling. The missing mass has not yet been detected. The presence of some absorbing matter such as dust grains and a diffused warm medium may account for the missing mass.