Diffuse Hot Plasma in the Interstellar Medium and Galactic Outflows

Manami Sasaki, Gabriele Ponti, Jonathan Mackey

Submitted on 4 July 2022


We summarise observations and our current understanding of the interstellar medium (ISM) in galaxies, which mainly consists of three phases: cold atomic or molecular gas and clouds, warm neutral or ionised gas, and hot ionised gas. These three gas phases form thermally stable states, while disturbances are caused by gravitation and stellar feedback in form of photons and shocks in stellar winds and supernovae. Hot plasma is mainly found in stellar bubbles, superbubbles, and Galactic outflows/fountains and is often dynamically unstable and is over-pressurised. In addition, in galactic nuclear regions, accretion onto the supermassive black hole causes enhanced star formation, outflows, additional heating, and acceleration of cosmic rays.


Comment: To appear in the Section 'Supernovae, Supernova Remnants, and Diffuse Emission' (Section eds.: Aya Bamba, Keiichi Maeda, Manami Sasaki) in the Handbook of X-ray and Gamma-ray Astrophysics (Eds. Cosimo Bambi, Andrea Santangelo)

Subjects: Astrophysics - High Energy Astrophysical Phenomena; Astrophysics - Astrophysics of Galaxies