Institute of Astronomy

Models of Diffuse Ionised Gas in star-forming galaxies

SpeakerTalk DateTalk Series
Bert Vandenbroucke (University of St Andrews)8 May 2019Institute of Astronomy Seminars


Star-forming galactic discs contain an extended layer of diffuse gas
that is photoionised, commonly referred to as the Warm Ionised Medium
(WIM) in our own Milky Way, and as the Diffuse Ionised Gas in general.
Large Halpha surveys have extensively mapped the properties of the DIG
and found typical scale heights of up to ~kpc above the plane of the
disc, and high intensities for forbidden line emission from [NII] 6584
and [SII] 6725 that indicate an increase in temperature with height
above the disc. To understand these properties and to pinpoint the
sources responsible for ionising the DIG, extensive 3D modelling is
required. In this talk, I will briefly review our knowledge of the DIG
and show how 3D Monte Carlo radiation transfer and (more recently)
radiation hydrodynamics models can help us understand (a) the observed
ionisation state of the DIG, and (b) the presence of a diffuse layer at
the observed heights above the galactic plane


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