bias; galaxies quenched at lower redshift tend to be larger than their counterparts at early times, which may drive much of the observed size evolution (e.g. Poggianti et al. 2013; Carollo et al. 2013).

From a theoretical perspective, the formation of ultra-compact massive spheroids requires the concentration of vast reservoirs of cool gas via dissipation, which can radiate and collapse to very high densities. A variety of models have arisen to explain spheroid formation in detail, with some invoking gas-rich mergers (e.g. Hopkins et al. 2009; Wellons et al. 2015) while others use the inflow of gas through cold streams, feeding an extended disc that eventually becomes unstable and contracts (e.g. Dekel et al. 2009; Zolotov et al. 2015). Outflows driven by AGN or star formation may then terminate the star formation by expelling the remainder of the gas (e.g. Hopkins et al. 2005).

In this work we explore the relationship between the quenching of distant galaxies and their structural transformation. We focus in particular on the rare class of “post-starburst” (PSB) galaxies, which are observed a few hundred Myr after a major episode of star formation was rapidly quenched. In the local Universe PSBs are identified from characteristic strong 