Extended Data Fig. 10: Merger history of submm galaxies using EAGLE cosmological simulation.

a, Stellar mass and redshift distribution of the submm galaxy sample (orange symbols). b, SFR of the submm sample (shown by orange symbols) relative to the star-forming main sequence of the simulations (solid blue line; all trends rescaled in star formation to z = 1 for clarity). Dark grey shaded regions mark the 16th–84th percentiles of the relation, whereas light grey shaded regions indicate the 5th–95th percentiles. Individual SFRs of the submm sample have been renormalized (see text). c, Fraction of submm galaxies that underwent major (blue symbols) or minor (grey symbols) mergers. The panel shows that major mergers do not seem to dominate the assembly of submm-bright galaxies. d, Gas accretion rates of galaxies before they became submm bright. The accretion includes diffuse gas and minor and (rare) major mergers. Blue symbols indicate the median rates of a control sample, consisting of galaxies with stellar masses within ±0.2 dex of the median stellar mass of the submm galaxies. This panel indicates that the submm event was probably triggered by a high rate of gas inflow. e, Disk-to-total (D/T) mass ratio of all galaxies at z = 0. Orange symbols highlight the D/T ratio of the z = 0 descendants of the submm galaxies. f, Similar to panel e, stellar [α/Fe] (represented by [O/Fe]) of all galaxies at z = 0, as well as of the submm descendants. Panels e and f indicate that submm galaxies evolve into elliptical galaxies with typical [α/Fe] element ratios.