Evolution of the anti-truncated stellar profiles of S0 galaxies since z = 0.6 in the SHARDS survey

Abstract

Context. Anti-truncated lenticular galaxies (Type-III S0s) present tight scaling relations between their surface brightness photometric and structural parameters. Although several evolutionary models have been proposed for the formation of these structures, the observations of Type-III S0 galaxies are usually limited to the local Universe. Aims. We aim to compare the properties of Type-III discs in a sample of S0 galaxies at 0.2 < z < 0.6 with those of the local Universe. In this paper, we study the evolution of the photometric and structural scaling relations measured in the rest-frame R-band with z and the possible differences between the rest-frame (B − R) colours of the inner and outer disc profiles. Methods. We make use of a sample of 14 Type-III E/S0–S0 galaxies at 0.2 < z < 0.6 from the GOODS-N field identified and characterised in a previous paper. We study whether or not the correlations found in local Type-III S0 galaxies were present ~6 Gyr ago. We analyse the distribution of the surface brightness characteristic parameters (Rbreak, μbreak, hi, ho, μ0,i and μ0,o) as a function of the stellar mass and look to see if there is a significant change with z. We also derive their rest-frame (B − R) colour profiles. Finally, we compare these results with the predictions from a grid of SSP models. Results. We find that the inner and outer scale-lengths of Type-III S0 galaxies at 0.4 < z < 0.6 follow compatible trends and scaling relations with those observed in local S0 galaxies as a function of the break radius, Rbreak. We do not detect any significant differences between the location of Rbreak between z ~ 0.6 and z ~ 0 for a fixed stellar mass of the object, whereas the surface brightness at the break radius μbreak is ~1.5 mag arcsec-2 dimmer in the local Universe than at z ~ 0.6 for a fixed stellar mass. We find no significant differences in the (B − R) colour between the inner and outer profiles of the Type-III S0 galaxies at 0.2 < z < 0.6. Conclusions. In contrast to Type-II (down-bending) profiles, the anti-truncated surface brightness profiles of S0 galaxies present compatible Rbreak values and scaling relations during the last 6 Gyr. This result and the similarity of the colours of the inner and outer discs point to a highly scalable and stable formation process, probably more related to gravitational and dynamical processes than to the evolution of stellar populations.