Left: spatially resolved Schmidt-Kennicutt law in PLCK G244.8+54.9 (red stars) and best fit relation (solid black line). The lower and upper black star indicate the luminosity-weighted average position of images #2.1 and #1.1, respectively. Other symbols indicate: submillimeter galaxies at z ~ 2 (green upside-down triangles, Bothwell et al. 2010), local starbursts (black circles, Kennicutt 1998), spatially-resolved data from the Eyelash (dark green triangles Swinbank et al. 2011) and SDP.81 (yellow squares, Hatsukade et al. 2015). The green and dark blue dashed lines indicate the Schmidt-Kennicutt relationship for high-z starburst galaxies and main sequence galaxies of Daddi et al. (2010), respectively. All star-formation rates are given for a Chabrier initial mass function, and are a factor 1.8 lower than in many other figures showing the Schmidt-Kennicutt relationship (see text for details). Right: same Schmidt-Kennicutt diagram, showing the position of maximum starbursts in several models, and the position of the Ruby relative to them. Light blue circles indicate nearby Eddington-limited starbursts (Andrews & Thompson 2011). The dark green solid lines show the mechanical input from stellar winds and supernova remnants for 100% and 50% efficiency, respectively. The dark blue lines and yellow hatched region show the models of Andrews & Thompson (2011) for an Eddington-limited starburst with a range of opacities between 10 and 30 cm² g^-1. Solid lines show the optically thick limit above the critical gas-mass surface density for the optically thick case, dashed lines the optically thin case below that limit. The solid blue line shows the relationship of Ostriker & Shetty (2011), also for optically thick and optically thin gas. The red line shows the model of Faucher-Giguère et al. (2013).