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تسجيل مستخدم جديدEvolution of the Luminosity Function, Star Formation Rate, Morphology and Size of Star-forming Galaxies Selected at Rest-frame 1500A and 2800A
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Tomas Dahlen
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Using the multiwavelength photometric and spectroscopic data covering the CDF-S obtained within the GOODS, we investigate the rest-frame UV properties of galaxies to z~2.2, including the evolution of the luminosity function, the luminosity density, star formation rate (SFR) and galaxy morphology. We find a significant brightening (~ 1 mag) in the rest-frame 2800A characteristic magnitude (M*) over the redshift range 0.3<z<1.7 and no evolution at higher redshifts. The rest-frame 2800A luminosity density shows an increase by a factor ~4 to z~2.2. We estimate the SFR to z~2.2 from the 1500A and 2800A luminosities. The SFR derived from the 2800A luminosity density is almost factor two higher than that derived from the 1500A luminosities. Attributing this to differential dust extinction, we find that an E(B-V)=0.20 results in the same extinction corrected SFR from both 1500A and 2800A luminosities. We investigate the morphological composition of our sample by fitting Sersic profiles to the galaxy images at a fixed rest-frame wavelength of 2800A at 0.5<z<2.2. We find that the fraction of apparently bulge-dominated galaxies (Sersic index n>2.5) increases from ~10% at z~0.5 to ~30% at z~2.2. At the same time, we note that galaxies get bluer at increasing redshift. This suggests a scenario where an increased fraction of the star formation takes place in bulge-dominated systems at high redshift. This could be the evidence that the present day ellipticals are a result of assembly (i.e., mergers) of galaxies at z>1. Finally, we find that galaxy sizes for a luminosity selected sample evolves as (1+z)^{-1.1} between redshifts z=2.2 and z=1.1. This is consistent with previous measurements and suggests a similar evolution over the redshift range 0 < z < 6.
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