Intergalactic Heating Induced by Streaming Cosmic Rays in the Early Universe
S.L. Yokoyama* and Y. Ohira
Pre-published on:
July 25, 2023
Published on:
September 27, 2024
Abstract
Our Universe has undergone a transition from a cold and neutral state to a hot and ionized state. In the standard picture, this transition is caused by UV and X-ray photons emitted by stars and galaxies. However, cosmic rays (CRs) can also contribute to the heating and ionization of the cosmic gas. It is suggested that CRs are accelerated in the early Universe in the supernova remnants of the first stars, just as they are in the current Universe. Although it has been pointed out that ionization by CRs raises the global temperature of the intergalactic medium by $10$ to $200 \, \mathrm{K}$, in our previous work, we found that the heating rate of resistive heating induced by streaming CRs can exceed that of ionization heating. The resistive heating is caused by the electron return current induced by streaming CRs. In this work, we study the heating around a galaxy, which is the source of photons and CRs, including the photo-heating, CR ionization heating, and CR resistive heating. It is shown that the gas in the vicinity of the galaxy is rapidly heated up to $\sim 10^4 \, \mathrm{K}$ by CR resistive heating.
DOI: https://doi.org/10.22323/1.444.0156
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