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Astro Seminar

Observations and simulations of diffuse ionised gas in galaxies

Speaker: Dr Kenny Wood (St Andrews)
Date: Wednesday 5 February 2020
Time: 14:00
Venue: Queens Buildings N/3.28

Widespread diffuse ionised gas is observed in the Milky Way and dozens of other galaxies. Large surveys of galaxies in H-alpha and other optical emission lines are now allowing for the study of the ionisation, temperature, dynamics, and spatial distribution of the diffuse ionised gas in galaxies with a wide range of star formation rates. This low density, almost fully ionised gas extends to altitudes of many kilo-parsecs above galactic mid planes, is a major constituent of galaxies accounting for about a third of the hydrogen in the interstellar medium and about half of the observed H-alpha emission from galaxies. The heating and ionising sources and means of supporting the gas at large altitudes have been a long standing theoretical problem, with observations demanding analysis with three dimensional simulations of radiation magneto hydrodynamics. I will review observations and properties of diffuse ionised gas and show new results from our radiation hydrodynamics simulations that include photoionisation feedback from OB stars and provide the first fully self consistent models of the ionisation state and temperature structure of the gas.