On the nature of diffuse ionized gas in galaxies -- I The contribution of dust scattering to diffuse line emission

Understand

In this work, we investigate the contribution of dust scattering to the diffuse H-alpha emission observed in nearby galaxies.

• As initial conditions for the spatial distribution of HII regions, gas, and dust, we take three Milky Way-like galaxies from state-of-the-art cosmological hydrodynamical simulations that implement different prescriptions for star formation, feedback, and chemical enrichment.
• Radiative transfer has been solved a posteriori, using the publicly-available Monte Carlo code Sunrise to take into account dust absorption and scattering of the H-alpha photons, originating exclusively from the HII regions.
• No contribution from recombinations in the diffuse ionized gas (DIG) component is explicitly or implicitly included in our model.