We combine new CO(1-0) line observations of 24 intermediate redshift galaxies (0.03<z<0.28) along with literature data of galaxies at 0<z<4 to explore scaling relations between the dust and gas content using polycyclic aromatic hydrocarbon (PAH) 6.2{mu}m (L_6.2_), CO(L'CO), and infrared (L_IR_) luminosities for a wide range of redshifts and physical environments. Our analysis confirms the existence of a universal L_6.2_-L'CO correlation followed by normal star-forming galaxies (SFGs) and starbursts (SBs) at all redshifts. This relation is also followed by local ultraluminous infrared galaxies that appear as outliers in the L_6.2_-L_IR_ and L_IR_-L'CO relations defined by normal SFGs. The emerging tight ({sigma}~0.26dex) and linear ({alpha}=1.03) relation between L_6.2_ and L'CO indicates a L_6.2_ to molecular gas (M_H2_) conversion factor of {alpha}6.2=M_H2_/L_6.2_= (2.7+/-1.3)x{alpha}CO, where {alpha}CO is the L'CO to M_H2_ conversion factor. We also find that on galaxy integrated scales, PAH emission is better correlated with cold rather than with warm dust emission, suggesting that PAHs are associated with the diffuse cold dust, which is another proxy for M_H2_. Focusing on normal SFGs among our sample, we employ the dust continuum emission to derive M_H2_ estimates and find a constant M_H2_/L_6.2_ ratio of {alpha}6.2=12.3M_{sun}/L{sun} ({sigma}~0.3dex). This ratio is in excellent agreement with the L'CO-based M_H2_/L_6.2_ values for {alpha}CO=4.5M_{sun}/(K km/s/pc^2^) which is typical of normal SFGs. We propose that the presented L_6.2-L'CO and L_6.2_-M_H2_ relations will serve as useful tools for the determination of the physical properties of high-z SFGs, for which PAH emission will be routinely detected by the James Webb Space Telescope.

Cone search capability for table J/MNRAS/482/1618/table3 (General properties of the 5MUSES sample)

Cone search capability for table J/MNRAS/482/1618/table4 (Galaxies from the literature with PAH, IR, and/or CO emission)