2019-02-27 Abstract
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Title: Large-scale outflows from starforming galaxies and cosmic-ray heating in protogalactic environments
Speaker: Prof. Kinwah Wu (Mullard Space Science Laboratory, University College London, UK)
Date: February 27 at 10:00
Location: R521, General building II
Abstract:
Galaxies (in the local Universe) with strong star-forming activity often show large-scale outflows. The outflows are powered by supernova events, a consequence of the star-formation process within the galaxies. These galaxy-scale outflows are multi-phase, multi-component media, consisting of a mixture of ionised and neutral gases, in the form of hot bubbles as well as cold, dense clumps. The outflows may also be laden with fine particles, such as dusts, and are permeated by tangled magnetic fields. The dynamics and hydrodynamics of such galactic-scale flows are therefore complex, yet they determine the feedback in the star-formation process. They also deliver chemically enriched material and energy to the environments, regulating the chemistry and the energy budget of the circum-galactic environments. Protogalaxies with strong star formation activity would also have large-scale outflows. These outflows are also powered by supernova events. The supernovae not only provide the energy to drive the galactic outflows but they also generate shocks which accelerate charged particles to the ultra-relativistic energies, i.e. UHE cosmic rays (CRs). The UHE CRs will interact with their host galaxies, causing heating of the interstellar medium. Some of the UHE CRs may be advected out from the galaxies, causing
heating of the circum-galactic medium. In this talk I will discuss the properties of multi-phase, multi-component protogalactic outflows and CR heating in the protogalactic environment in the presence of large-scale outflows. I will show the new results of the recent calculations of my group and discuss the astrophysical implications.