The evolution (or not) of the star formation efficiency, dust content, and duty cycle of high-z galaxies

Wednesday November 11th 2020 @12pm, Zoom Colloquium
Dr Jordan Mirocha McGill University

Email: jordan.mirocha[at]


A relatively simple model has emerged in recent years that can explain the bulk properties of high redshift galaxies: star formation is fueled by the inflow of pristine material from the intergalactic medium, and proceeds with an efficiency that depends strongly on the mass of a galaxy’s parent dark matter halo but not obviously on cosmic time. We generally interpret this mass dependence as a signature of stellar feedback despite the fact that stellar feedback models also predict time evolution in the star formation efficiency. In this talk, I’ll focus on this apparent tension, and show that to remain in agreement with observations, competing feedback scenarios require qualitatively different assumptions about the properties of dust and the duty cycle of star formation in galaxies. As a result, I’ll discuss the prospects for distinguishing models based on the ‘dustiness’ and ‘burstiness’ of galaxies found in upcoming galaxy surveys with JWST and ALMA, and potentially via constraints on reionization from future 21-cm experiments.