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|Paper IPM / Astronomy / 14762||
We study the history from zâ¼2 to zâ¼0 of the stellar mass assembly of quiescent and star-forming galaxies in a spatially resolved fashion. For this purpose we use multi-wavelength imaging data from the Hubble Space Telescope (HST) over the GOODS fields and the Sloan Digital Sky Survey (SDSS) for the local population. We present the radial stellar mass surface density profiles of galaxies with Mâ>1010Mâ, corrected for mass-to-light ratio (Mâ/L) variations, and derive the half-mass radius (Rm), central stellar mass surface density within 1 kpc (Î£1) and surface density at Rm (Î£m) for star-forming and quiescent galaxies and study their evolution with redshift. At fixed stellar mass, the half-mass sizes of quiescent galaxies increase from zâ¼2 to zâ¼0 by a factor of â¼3â5, whereas the half-mass sizes of star-forming galaxies increase only slightly, by a factor of â¼2. The central densities Î£1 of quiescent galaxies decline slightly (by a factor of â²1.7) from zâ¼2 to zâ¼0, while for star-forming galaxies Î£1 increases with time, at fixed mass. We show that the central density Î£1 has a tighter correlation with specific star-formation rate (sSFR) than Î£m and for all masses and redshifts galaxies with higher central density are more prone to be quenched. Reaching a high central density (Î£1â³1010Mâkpc2) seems to be a prerequisite for the cessation of star formation, though a causal link between high Î£1 and quenching is difficult to prove and their correlation can have a different origin.
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