Sample interview questions: Can you explain the concept of cosmic rays and their role in the heating of intergalactic gas?
Sample answer:
Cosmic Rays and Heating of Intergalactic Gas
Cosmic rays are highly energetic particles, primarily protons and nuclei, that originate from various sources in the universe. They travel at nearly the speed of light and possess energies ranging from a few MeV to several EeV.
In intergalactic space, a significant fraction of cosmic rays interact with the diffuse intergalactic medium (IGM), which is a hot, tenuous gas. These interactions can heat the IGM through several mechanisms:
- Photoheating: Cosmic rays produce gamma rays and other high-energy photons through interactions with the IGM. These photons can heat the gas through photoelectric effect and Compton scattering.
- Collisional heating: Cosmic rays can directly transfer energy to the IGM gas through collisions. This is more significant for cosmic rays with lower energies (less than a few GeV), as their mean free path is shorter.
- Ionization heati… Read full answer