BEXCO - Room A(101/102)
[CRD002] Cosmic rays in early star-forming galaxies and their effects of the interstellar medium
- Ellis OWEN
- Ellis OWEN (Mullard Space Science Laboratory, University College London, United Kingdom)
High-redshift galaxies with strong star formation activity are likely sources of cosmic ray particles. At high-energies, these particles interact with the matter density and radiation fields of the galactic environment via hadronuclear, photo-pair and photo-pion processes to produce charged and neutral pions, neutrons and protons. The effect of these interactions is for the cosmic rays to deposit energy into their host environment as they propagate through the multi-component interstellar medium (ISM). We show how energy transport and deposition by ultra high-energy cosmic rays is regulated by the evolution of the galaxy, in particular by the development of the galactic magnetic field. We show how the particle-driven energy deposition can influence the thermal evolution of the host and its surroundings and demonstrate that at early times, before a galactic magnetic field has emerged, there is a short window of time in which cosmic ray particles may freely stream into intergalactic space. Using a diffusion approach in a simple parametric model of a protogalaxy, we calculate how high-energy cosmic rays can be increasingly contained within a galaxy to concentrate a heating effect towards the ISM and outline some of the implications of this process.