The wavelength dependence of the Fundamental Plane projection along the velocity dispersion axis, namely the Kormendy relation, is well characterised at low-redshift, but poorly studied at intermediate redshifts. The Kormendy relation provides information on the evolution of the population of early-type galaxies (ETGs), therefore, by studying it, we may shed light on the assembly processes of these objects and their size evolution. Since studies at different redshifts are generally conducted in different rest-frame wavebands, investigating whether there is a wavelength dependence of the Kormendy relation is fundamental to interpret the conclusions we might draw from it. We analyse the Kormendy relations of the three Hubble Frontier Fields clusters, Abell S1063, at z=0.348, MACS J0416.1-2403, at z=0.396, and MACS J1149.5+2223, at z=0.542, as a function of wavelength. This is the first time the Kormendy relation of ETGs has been explored consistently in such a large range of wavelength at intermediate redshifts. We exploit very deep Hubble Space Telescope photometry, ranging from the observed B-band to the H-band, and VLT/MUSE integral field spectroscopy. We improve the structural parameters estimation we performed in a previous work (Tortorelli et al., 2018MNRAS.477..648T, Cat, J/MNRAS/477/648) by means of a newly developed Python package called morphofit (Tortorelli & Mercurio 2023). Results: With its use on cluster ETGs, we find that the Kormendy relation slopes smoothly increase with wavelength from the optical to the near-infrared bands in all three clusters, with the intercepts getting fainter at lower redshifts due to the passivisation of the ETGs population. The slope trend is consistent with previous findings at lower redshifts. The slope increase with wavelength implies that smaller size ETGs are more centrally concentrated than larger size ETGs in the near-infrared with respect to the optical regime. Since different bands probe different stellar populations in galaxies, the slope increase also implies that smaller ETGs have stronger internal gradients with respect to larger ETGs.

Cone search capability for table J/A+A/671/L9/as1063 (7-band structural parameters for 95 galaxies)

Cone search capability for table J/A+A/671/L9/m0416 (7-band structural parameters for 119 galaxies)

Cone search capability for table J/A+A/671/L9/m1149 (7-band structural parameters or 68 galaxies)