Question

Where is most of the baryonic of the universe found?

Answer 1

Most of the baryonic matter in the universe is found in the form of gas, primarily in the intergalactic medium and within galaxies. Baryonic matter includes ordinary matter such as protons, neutrons, and electrons, which constitutes stars, planets, and the interstellar and intergalactic gas.

A significant portion of this baryonic matter resides in:

1. **Stars**: They account for a considerable fraction of baryonic matter.
2. **Gas in Galaxies**: In galaxies, a large amount of baryonic matter exists in the interstellar medium as hydrogen and helium gas, along with dust and other elements.
3. **Intergalactic Medium**: There is also a substantial amount of baryonic matter in the form of hot, dilute gas located between galaxies in the intergalactic medium.

While baryonic matter constitutes about 5% of the total energy density of the universe, it is mostly in a diffuse state rather than concentrated in structures like stars and galaxies. The distribution primarily reflects the history of the universe's evolution, with many baryons existing in less dense regions outside of galaxies.