COLLOQUIUM Yu Fung Wong (University of Hong Kong)

Gas heating, cooling and chemistry in the cold interstellar medium : effects of radiation field and cosmic rays

Understanding the thermodynamics and chemistry of cold interstellar gas is crucial to a better understanding of the dynamical evolution of the interstellar medium, star formation and the line emission spectra of galaxies. I give an overview of gas heating and gas cooling processes, and also gas-phase carbon chemistry of the cold interstellar medium.

Then, I introduce a new self-consistent thermochemical code, which predicts the abundances of chemical species and the emission of observationally significant cooling lines from inputs of pressure, radiation field, metallicity and cosmic-ray ionisation rate. Using the code, I show that cosmic-ray ionisation can boost the grain photoelectric heating rate by lowering the charge of dust grains. I also demonstrate that optical photons can have a significant effect on gas heating and CO line emission in environments similar to the Central Molecular Zone of the Milky Way.

Understanding the thermodynamics and chemistry of cold interstellar gas is crucial to a better understanding of the dynamical evolution of the interstellar medium, star formation and the line emission spectra of galaxies. I give an overview of gas heating and gas cooling processes, and also gas-phase carbon chemistry of the cold interstellar medium.

Then, I introduce a new self-consistent thermochemical code, which predicts the abundances of chemical species and the emission of observationally significant cooling lines from inputs of pressure, radiation field, metallicity and cosmic-ray ionisation rate. Using the code, I show that cosmic-ray ionisation can boost the grain photoelectric heating rate by lowering the charge of dust grains. I also demonstrate that optical photons can have a significant effect on gas heating and CO line emission in environments similar to the Central Molecular Zone of the Milky Way.

Talk in presence and via Zoom:

https://uni-hamburg.zoom.us/j/66006535328?pwd=aGkrSjJIYmZjK0VpYlpGL0ZrdHg2UT09