An over-abundance of quenching: comparing observations and simulations of low mass galaxies with Orchard

Claire Dickey (Yale)
Friday, April 23, 2021 - 2:00pm to 3:00pm

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 a 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. Building on this methodology, I then explore the quiescent satellites around Milky Way-like galaxies as observed by the SAGA survey to understand the quenching of low mass galaxies as a function of environment. 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.

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