Radial distribution of near-UV flux in disc galaxies in the range 0 ≲ z ≲ 1

Context. In the last 8 Gyr of cosmic time the global star formation rate (SFR) has declined by roughly an order of magnitude, and most of this activity has been progressively confined to ever less massive galaxies (downsizing). Previous studies show that the main drivers of the decline in the global SFR are the spiral galaxies. However, we still lack a detailed understanding of how the star formation (SF) has changed as a function of position within the discs. Such studies will help to build a more accurate picture of how stellar discs are formed and grow. Aims. The goal of this paper is to quantify the changes in the SF distribution within the disc galaxies in the last similar to 8 Gyr. As a proxy for the SF radial profile, we use the near-UV surface brightness distributions, suitably allowing for extinction. Methods. We compare the effective radii (R-eff) and concentration of the flux distribution in the rest-frame near-UV (NUV-GALEX band) for a sample of 270 galaxies in the range 0 < z < 1. This radial distribution is compared to that measured in the rest-frame B-band, which traces older stellar populations. The analysis is performed using deep, high-resolution, multi-band images from GALEX, SDSS, and HST/ACS-GOODS-South. Results. The relation R-eff(NUV)-M-star suffers a moderate change between z similar to 1 and z similar to 0, at a fixed stellar mass of 10(10) M-circle dot galaxies increase their effective radii by a factor 1.18 +/- 0.06. The ratio R-eff(NUV)/R-eff(B) has increased by similar to 10% in the same period. Median profiles in NUV show signs of truncation at R similar to R-eff, and median colour profiles (NUV-B) show a minimum (a bluest point) also around R similar to 1-1.5R(eff). The surface brightness of the discs (at R-eff) has decreased by similar to 80% in NUV, and by similar to 60% in B since z similar to 1. The distributions of NUV flux are more compact at z similar to 1 than nowadays, in terms of the fraction of flux enclosed in a specific radius (in kpc). The central brightness in B and NUV has increased with respect to the brightness level of the discs, both in B and NUV, perhaps indicating a continuous accumulation of the bulge structure since z similar to 1, or that they have been left exposed because of the significant decline in the star-forming activity in the discs. Conclusions. Our results indicate that the SF surface density has decreased dramatically in discs since z similar to 1, and this decline has been more intense in the central parts (less than or similar to R-eff) of the galaxies. In addition, our data suggest that the bulges/pseudo-bulges have grown in surface brightness with regard to the discs since z similar to 1.