Poster - Splinter JungeAG

Tuesday, 12 September 2023, 15:30   (H 3007)

Sink formation criteria on galaxy scale simulations

Pierre Colin Nürnberger, Stefanie Walch
1st Institute of Physics, University of Cologne

Given their low mass and smaller physical size, dwarf galaxies offer an ideal laboratory to test the impact of different physical processes with sufficient resolution while including the galactic environment which provides shear and global dynamical features. Many such simulations have been performed in the recent years to gain insights into e.g. metal enrichment, star formation and the effects of stellar feedback mechanisms. Previously published simulations use a stochastic approach to realize star formation which converts part of the gas to stellar mass using a fixed conversion efficiency factor. In this work, we use the sink particle formalism, which improves upon the stochastic approach by accounting for the self-consistent formation of star clusters and is commonly used in smaller scale ISM simulations. We simulate an isolated low-mass dwarf galaxy implemented in the magneto-hydrodynamics code FLASH with a resolution of up to 5 pc. All simulations contain self-gravity, an on-the-fly non-equilibrium chemical network, radiative transfer and a static dark matter potential. The galaxy is initially set up to be in hydrostatic equilibrium and turbulence is driven using randomly positioned supernovae (SNe) at a rate of 0.5 Myr-1. We follow the formation of stars using either the default sink formalism or a reduced version of the formation criteria which neglects the checks for a gravitational potential minimum and the convergent flow of the surrounding gas. We also study the impact of SN feedback with and without the inclusion of ionizing radiation from massive stars (m* >= 9 M☉) which is computed using the TreeRay radiative transfer method. We find that the reduced sink formalism performs better and creates more realistic stellar population, with sinks having a wider spatial and mass distribution in comparison to the default sink formalism. Additionally, the reduced formalism both decreases and delays mass and energy loading factors. This is further enhanced by the inclusion of ionizing radiation. Independent of the formalism the overall star formation rate (SFR) stays almost unchanged and show a strong decrease with the inclusion of ionizing radiation. Overall, we find that the more relaxed "reduced" sink formalism to better capture the formation of stellar clusters and propose this prescription for galaxy scale simulations where higher resolutions can not be feasibly achieved. Additionally, the inclusion of ionizing radiation feedback plays a vital role in regulating the SFR.