Dr. Ellis Owen (University College London)
"The implications of cosmic ray heating in and around the interstellar medium of high-redshift starbursts"
High-redshift star forming galaxies are complex multi-phase systems where hot interstellar gas, cold dense molecular clouds and energetic particles (i.e. cosmic rays) all coexist. These starburst galaxies are especially likely to be environments abundant in high-energy cosmic rays due to the presence of massive stars and their remnants. Stellar remnants can supply seed particles and generate the shocks (via supernova explosions and other violent events) needed to accelerate the seeds to very high energies. This talk considers the interplay of interactions between the ambient partially ionized gases, dense clouds, and the energetic non-photonic cosmic ray particles in these environments. We calculate the energy deposition by cosmic rays as they propagate though their host galaxy and beyond, accounting for their high-energy hadronic interactions with interstellar matter and the influence of developing galactic magnetic fields. We show how this deposited energy affects the thermal conditions of the host galaxy and the region in which the host galaxy resides. We argue that cosmic ray induced heating processes can contribute to the development of a diffuse Lyman-alpha emitting halo such as those recently observed around star forming galaxies, and this corresponds to the region of cosmic ray containment around the host galaxy as its magnetic field evolves.