Abstract

Contributed Talk - Plenary

Estimating the Molecular Gas Depletion Time in Dwarf Galaxy Simulations

Alice Coors
University of Cologne

On galactic scales, the star formation rate surface density ΣSFR is correlated with the molecular gas surface density ΣH2. This follows a power relation known as the Kennicutt-Schmidt law. The ratio of these two values is the depletion time τdep = ΣH2 / ΣSFR with a common value of 2 Gyr. Schruba et al. (2010) demonstrated that the depletion time diverges for small spatial scales. When focusing on gas regions, the depletion time tends to be overestimated, whereas focusing on star-forming regions leads to an underestimation. To address this, Kruijssen & Longmore (2014) developed a fit method for the resulting discrepancy, enabling the retrieval of characteristic star formation timescales. In this project, we estimate the molecular gas depletion time in simulations of dwarf galaxies with solar metallicity. We use CO as a tracer for gas regions and Hα as a tracer for star formation. We apply the conditions outlined in Schruba et al. (2010) to identify CO and Hα peaks and see that the relation ΣSFR ∼ ΣH2 breaks down on small scales in a dwarf galaxy with solar metallicity. Furthermore, we compare the evolution of SFR, gas surface density, and gas depletion time over four simulation runs with varying feedback mechanisms and sink particle formation conditions and interpret the results. In addition, we apply the fit methods introduced by Kruijssen et al. (2018) and Koda & Tan (2023). We find that some simulation snapshots yield inconsistent results, as the duration of the gas phase is not always directly proportional to the average depletion time.