Relation between FWHM of the CO(1−0) line and for cluster (circles) and field galaxies (stars). High-redshift sources, those with z > 1, are indicated by filled symbols while sources with z < 1 are indicated by hollow ones. The color-coding used in the figure is as follows: intermediate-z ULIRGs (red hollow stars Magdis et al. 2014), normal SFGs at z = 1.5 (blue filled stars Daddi et al. 2010a; Aravena et al. 2014), and SMGs (large and small red filled stars from Ivison et al. 2011; Bothwell et al. 2013, respectively). References for cluster sources can be found in Sect. 5.2 and Table A.1. The mode of star formation for each source is color-coded as blue for “disk-like” and red for “starburst”. The solid line shows the relation from Bothwell et al. (2013). The dashed line assumes the typical radius for disk galaxies. Both high-z population, dusty starbursts, and disk-like galaxies show a unique correlation between CO luminosity and line width with significant scatter (~0.3 dex).