Spatial distribution of stellar mass and star formation activity at 0.2 < z < 1.2 across and along the main sequence

Abstract

High-resolution multi-wavelength photometry is crucial to explore the spatial distribution of star formation in galaxies and understand how these evolve. To this aim, in this paper we exploit the deep, multi-wavelength Hubble Space Telescope (HST) data available in the central parts of the Great Observatories Origins Deep Survey (GOODS) fields and study the distribution of star formation activity and mass in galaxies located at different positions with respect to the main sequence (MS) of star-forming galaxies. Our sample consists of galaxies with stellar mass ≥109.5 M⊙ in the redshift range 0.2 ≤ z ≤ 1.2. Exploiting 10-band photometry from the UV to the near-infrared at HST resolution, we derived spatially resolved maps of galaxy properties, such as stellar mass and star formation rate and specific star formation rate, with a resolution of ∼0.16 arcsec. We find that the star formation activity is centrally enhanced in galaxies above the MS and centrally suppressed below the MS, with quiescent galaxies (1 dex below the MS) characterised by the highest suppression. The specific star formation rate in the outer region does not show systematic trends of enhancement or suppression above or below the MS. The distribution of mass in MS galaxies indicates that bulges grow when galaxies are still on the MS relation. Galaxies below the MS are more bulge-dominated with respect to MS counterparts at fixed stellar mass, while galaxies in the upper envelope are more extended and have Sérsic indices that are always smaller than or comparable to their MS counterparts. The suppression of star formation activity in the central region of galaxies below the MS hints at inside-out quenching, as star formation is still ongoing in the outer regions.