May 2015 • 2015ApJ...805...34M
Abstract • Using the Hubble Space Telescope (HST)/WFC3 and Advanced Camera for Surveys multi-band imaging data taken in CANDELS and 3D-HST, we study the general properties and diversity of the progenitors of the Milky Way (MWs) and local massive galaxy (MGs) at 0.5\lt z\lt 3.0, based on a constant cumulative number density analysis. After careful data reduction and stacking analysis, we conduct a radially resolved pixel spectral energy distribution fitting to obtain the radial distributions of the stellar mass and rest-frame colors. The stellar mass of MWs increases in a self-similar way, irrespective of the radial distance, while that of MGs grows in an inside-out way where they obtain ∼ 75% of the total mass at the outer (\gt 2.5 kpc) radius since z∼ 2. Although the radial mass profiles evolve in distinct ways, the formation and quenching of the central dense region (or bulge) ahead of the formation of the outer disk are found to be common for both systems. The sudden reddening of the bulge at z∼ 1.6 and z∼ 2.4 for MWs and MGs, respectively, suggests the formation of the bulge and would give a clue to the different gas accretion histories and quenching. A new approach to evaluate the morphological diversity is conducted by using the average surface density profile and its dispersion. The variety of the radial mass profiles for MGs peaks at higher redshift (z\gt 2.8) and then rapidly converges to a more uniform shape at z\lt 1.5, while that for MWs remains in the outer region over the redshift. Compared with the observed star-formation rates and color profiles, the evolution of variety is consistently explained by the star-formation activities.