Abstract

Poster - Splinter General   (Aula 1&2 / virtual plenum)

A subgrid model for the turbulent circumgalactic medium in massive, high redshift star-forming galaxies: Understanding the [CII] line emission

Lennart Buhlmann, Stefanie Walch-Gassner
University of Cologne

We introduce a subgrid model for galaxies and their halos in IllustrisTNG50 simulations. The model allows us to determine and analyse the [CII] emissions in TNG50. Our subgrid model is constructed with turbulent box simulations with the FLASH code. For our simulations, we apply a simple chemical network and use different initial conditions for the metallicity and density to generate a turbulent gas from the original homogeneous conditions within each Voronoi cell of TNG50. We transfer the outcomes from the different FLASH simulations to the individual cells in TNG50. This gives us a higher spatial resolution so that we can account for the existence of subgrid turbulence in TNG50. The amount of [CII] is determined using an analytical approach with the assumption that all gas is being optically thin. To validate this approach, we use the radiative transfer code RADMC-3D, which accounts for optical thickness. We compare the [CII] luminosities derived from both approaches and find good agreement. We then apply this subgrid model to the halos of gas-rich galaxies at high redshift ($zsim5$), calculate the surface brightness profile for one halo and compare this to observed profiles. Applying the subgrid model reproduces the qualitative shape of the profile from the observations. However, our fluxes are a factor of $sim 100$ too low. We discuss possible reasons for this discrepancy, such as a insufficient density or metallicity in the TNG50 halo or too low levels of turbulence. This may result in a lower number of dense clumps, which rims are [CII]-bright in our simulations. Additionally, we analyse the surface brightness profiles with respect to gas properties such as temperature and inflows or outflows of the galaxy. These results can be used for a further comparison with observations.