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tokens: of a disc and also contributed to the increase of the central BH mass. The analysis of the formation histories of eagle galaxies and its connection to the scatter of the MZR will be the subject of a forthcoming article (Zenocratti et al., in preparation). Sharma Theuns ( 2019 ) propose a model of self-regulated galaxy formation, in which the SFR, stellar mass, gas mass, and metallicity depend on halo mass, cosmological accretion rate, and redshift, but regulated by feedback. In their ‘Iκεα’ model, the main astrophysical parameter ε is a dimensionless measure of the efficiency of stellar feedback: a large value of ε implies efficient feedback and low SFR, while feedback is inefficient and the SFR is high for a small ε. This leads to the following scaling for Z and f g with M ⋆ and efficiency ε: where n ≈ 1.4 is the slope of the Kennicutt–Schmidt star formation law. These relations show that when feedback is efficient (meaning ε is large, ε ≈ 1), Z is low and f g is high, whereas, inefficient feedback (ε ≪ 1) implies Z is high and f g low. We can connect this to the morphology of the galaxy by speculating that feedback in a thin disc – corresponding to a galaxy with high κ co – is more efficient than when κ co is low (a more spheroidal gas distribution). High-resolution simulations that resolve individual supernova energy injections in gas columns suggest this type of relation between feedback efficiency and disc morphology. For example, the simulations by Creasey, Theuns Bower ( 2013 ) show that supernova explosions that occur above or below the disc are more efficient at driving winds, because cooling loses are suppressed when the explosion occurs at the lower densities that prevail there (see also Girichidis et al. 2016 ). Thus, in eagle , accretion of metal-poor gas seems to trigger the formation of a disc but, once the disc has already been formed, feedback effects would play a role in regulating the subsequent metallicity evolution. We leave the analysis of feedback effects on eagle disky galaxies for a future work. 5 CONCLUSIONS We analysed the MZR as a function of morpho-kinematical parameters in the eagle cosmological hydrodynamical simulations. At z = 0, we found new secondary dependences of metallicity on the internal kinematics and morphology of galaxies. At low masses (), higher metallicities are found for more spheroidal and lower rotation-supported galaxies. A preliminary analysis of the star formation histories of low-mass galaxies indicates that late accretion of metal-poor gas dilutes the metal content of galaxies, triggers their star formation activity, and contributes to the formation of the galaxy disc. When the gas is in a thin, rotationally supported disc, feedback may be more efficient, which results in lower O/H and a higher gas fraction (Sharma Theuns 2019 ). The trends in more massive galaxies are generally less strong, with lower metallicities found in more prolate galaxies with lower levels of rotational