Astronomy & Astrophysics Seminar: How Do Galaxies Interact With Their Surrounding Medium and How Do We Know It?

Zoom: https://tau-ac-il.zoom.us/j/89636068691?pwd=YkVoWG9laTFPZHVENWovQ1FWczUvQT09

Abstract:

Galaxies, which are the building blocks of the Universe, do not evolve as isolated systems. They interact with each other as well as with their surrounding medium. The aim of this talk will be to focus on the interaction between galaxies and their surrounding medium through high-energy particles or cosmic rays. These high-energy particles are accelerated in the galactic disk through star formation and supernova activities. Cosmic ray particles diffuse out of the galaxies, through scattering off magnetic irregularities, and interact with the circumgalactic and intergalactic medium (CGM and IGM). We have studied some aspects of these interactions, with the help of analytical calculations and numerical simulations, and have shown that cosmic rays can significantly change the properties of CGM and IGM. We predict how the production of a synchrotron background radiation from cosmic ray electrons at the cosmic dawn, as well as the heating of the IGM by cosmic-ray protons lead to a certain depth of the resulting (redshifted) 21 cm absorption. Furthermore, we quantify the dynamical effect of cosmic rays in driving galactic outflows and discuss its role in triggering inhomogeneity in the outflowing gas. I will also briefly summarise our ongoing work on the CGM-outflow interaction and its possibility to be detected in x-ray observations.

Seminar Organizer: Dr. Iair Arcavi