An overabundance of self-quenching in Orchard: comparing low mass galaxies in observations and simulations

Low mass, isolated galaxies present a unique opportunity to study a rare boundary condition in galaxy evolution. In the SDSS, all isolated galaxies with stellar mass below 10^9 Msun are star-forming. That is, there is a stellar mass threshold below which self-quenching processes appear to become inefficient. Motivated by these observations, I will present Orchard, a new methodology for building mock surveys of large volume, hydrodynamic simulations from the IQ Collaboratory. Using this framework, I measure the quenched fractions as function of stellar mass across three major numerical galaxy simulations (EAGLE, TNG, and SIMBA) and compare to observations. I find that even after accounting for observational and selection biases, all three simulations have an abundance of quiescent galaxies below the observed quenching threshold. Using Orchard, I then directly compare the star formation histories and quenching timescales derived from observations against those predicted by simulations. The framework presented here demonstrates a path towards more robust and accurate comparisons between theoretical simulations and galaxy survey observations, while the quenching threshold serves as a sensitive probe of feedback implementations.

Hosted by Pitt.