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Open Access Publications from the University of California

Resolved (KPC-Scale) Properties of Emission-Line Galaxies at Intermediate Redshifts

  • Author(s): Hemmati, Shoubaneh
  • Advisor(s): Mobasher, Bahram
  • et al.

The focus of this dissertation is to study resolved substructures in galaxies at kpc-scale and their relation with the global properties of the host galaxy using combined high resolution photometric data from the Hubble Space Telescope and very deep long exposure spectroscopic observations with the Keck telescopes. I use the optical and near-infrared data taken as part of the CANDELS project to perform pixel-by-pixel analysis of 120 galaxies at intermediate redshifts. I produce resolved rest-frame (U-V) color, stellar mass and star formation rate surface densities, stellar age and extinction maps and profiles along the galaxies rotation axes. I study physical properties of clumps and quantify their spatial distribution and covering fraction. Investigating the evolution of covering fraction and average radial distance with respect to both redshift and stellar mass of the host galaxy, suggests that if the central bulge growth is due to migration of stellar clumps, it should have happened at higher redshifts. I find that there exists a tight correlation between the stellar mass and star formation rate surface densities of pixels inside individual galaxies as well as among red and blue clumps over different galaxies. The tightness of the blue clumps main sequence regardless of the large redshift rang of the hosts, suggests no evolution in the nature of blue clumps with time. I estimate small-scale distribution of stellar dust extinction from pixel-by-pixel SED fitting and used $\rm H\alpha / H\beta$ nebular emission line ratios from Keck/DEIMOS spectra at each spatial resolution element to measure attenuation faced by ionized gas at different radii from the center of galaxies. I find a good agreement between the integrated and median of resolved color excess measurements in the galaxies. I find that inclination plays an important role in the variation of the nebular to stellar color excess ratio. I find that the nebular color excess increases with stellar mass surface density. This explains the absence of radial trend in the nebular color excess in lower mass galaxies. I also demonstrate the usefulness of resolved optical line ratio plots in identifying otherwise hidden AGNs.

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