Oral Presentation
Cosmic-rays, Lyman-alpha halos and molecular clouds in starbursting protogalaxies
Presenter: Ellis Owen (University College London - Mullard Space Science Laboratory)
Star-forming galaxies are complex multi-phase, multi-component systems, where cold dense molecular clouds, hot tenuous Lyman-alpha emitting gas and energetic thermal and non-thermal charged particles are found to co-exist. Recent observations revealed that many star-forming galaxies, nearby and far away, are enveloped by a Lyman-alpha halo. These Lyman-alpha halos could be produced by interactions between ambient gases and energetic non-photonic particles, i.e. cosmic rays, or by shock heating generated by ongoing star-forming activities in the galaxies. This talk addresses the interplay of interactions between high-energy cosmic-rays, X-rays, ionised and partially ionised gases and the dense media in starbursting protogalactic environments. We calculate the energy deposition by cosmic-rays and X-rays when they propagate through the galaxy of their origin to the host environment. We show how energy transport is regulated by the evolution of the galaxy and how the energy deposition affects the thermal conditions of the host galaxy, its neighbouring galaxies and the region where the host galaxy resides. We argue that combining the information obtained from high-energy (e.g. gamma rays via Fermi and IACTs, X-rays via XMM-Newton and Chandra), medium-energy (e.g. optical/IR via large ground-based telescopes) and low-energy (e.g. molecular lines via ALMA and other millimetre interferometers) studies will allow the evolution of complex interactions between the different phases of media in galaxies to be tracked over cosmic time.
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