Seminars at FGG
Constraining the Ionization Mechanisms of Extraplanar Diffuse Ionized Gas in low-SFR Galaxies
Speaker: Riku Rautio (University of Oulu, Finland)
Date and time: 2025-05-13 12:30
The study of extraplanar diffuse ionized gas (eDIG) is crucial for understanding many energetic phenomena that shape the evolution of late-type galaxies. This extended gas is primarily ionized by the radiation of midplane OB stars. However, eDIG often exhibits high ionization lines, which OB star ionization cannot account for. In our sample of eight edge-on galaxies observed with MUSE, NTT (ESO) and NOT, we discovered one galaxy (ESO 544-27) where the eDIG morphology and emission spectrum seem to indicate ionization by hot low-mass evolved stars (HOLMES). The eDIG properties of the other galaxies in the sample, that had less massive thick discs and higher star formation rates (SFR), were well explained by ionization by midplane OB stars. This seems to indicate that ionization of the eDIG by HOLMES is an important mechanism specifically for low-SFR galaxies. To investigate this further, we are extending our sample to include four additional low-SFR galaxies.