Intergalactic medium – Our space is filled with gas, which is the intergalactic medium. Its average density is less than 1 atom per cubic decimeter, yet the total mass of intergalactic gas may be greater than the mass contained in all stars.
Its climate is in the range of 10 million degrees Celsius, and it is heated by the stellar wind and the bursting shells of supernovae (see Stars, supernovae), which may be called the galactic wind or the electromagnetic radiation that results from the accretion of matter on black holes.
There is a large portion of interstellar gas that is concentrated in intergalactic clouds, which have significant differences from each other in density and temperature.
The chemical composition of intergalactic gas is endlessly varied. Among the objects found in the intergalactic medium have been hydrogen, helium, carbon and nitrogen atoms, oxygen, sulfur, and various metals. This is the reason why much of the intergalactic gas has been ejected from galaxies, and it is the product of the recycling of matter in the interior of stars (see Stars, evolution).
Through the study of the intergalactic medium, various problems related to the study of the evolution of the universe can be solved. The spectrum of intergalactic gas can be observed in the background of galaxies or other objects. When observing any thing, we see it as it was when the electromagnetic radiation left them. Radiation that has come from quasars that are billions of light years away from us gives a glimpse of what they were like billions of years ago. All gas clouds from quasar to Earth are in the field of view, allowing us to study their state over a wide range of time, and to obtain information about the evolution of the properties of intergalactic gas over many billions of years. The most likely way to relate individual gas clusters to their distance in light-years is to use the redshift of their spectrum lines. As a result, it may be possible to gain insight into how processes in the universe have evolved.
Intergalactic medium
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