Mapping Spatially Resolved Star Formation, Metallicity and Dust Across Galaxy Populations Over Cosmic Time
- Author(s): Jafariyazani, Marziye
- Advisor(s): Mobasher, Bahram
- et al.
In this thesis, I study the integrated and spatially resolved (kilo-parsec scale) properties of star-forming and quiescent galaxies across cosmic time to understand their evolution. First, using a sample of star-forming galaxies at intermediate redshifts (0.1 < z < 0.42) selected from the MUSE Wide Survey, I investigate the spatial distribution of H-alpha star formation rate (SFR) and the Balmer decrement using data from MUSE integral field spectrograph. For the same galaxies, I derive spatially resolved mass, SFR and dust maps from pixel-by-pixel Spectral Energy Distribution (SED) fitting on multiband photometric data from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) taken with the Hubble Space Telescope. I find strong dependence of the radial profiles of both stellar and nebular color excesses on the integrated specific SFR of star-forming galaxies. My results support the inside-out scenario for the growth of these galaxies. Next, I investigate the chemical abundances and star formation histories of high-redshift quiescent galaxies. My sample consists of five unique gravitationally lensed galaxies at 1.95 < z < 2.64 which includes MRG-M0138, the brightest lensed quiescent galaxy detected in the near infrared wavelengths. This is the only sample of quiescent galaxies at z ~ 2 for which we have a precise measure of stellar abundances as well as spatially resolved measurements, made possible due to strong gravitational lensing. I first analyze spectra of MRG-M0138 to measure magnesium-enhancement [Mg/Fe] (only the second precise [Mg/Fe] measurement at z~2), iron abundance [Fe/H] and, for the first time, their spatial gradient, as well as the stellar abundances of 6 other elements using full spectral fitting. I finally present my analysis of the other four galaxies in this sample where in addition to investigating their chemical abundances, I study their star formation histories reconstructed by fitting synthetic models to their multi-band photometric and spectroscopic data. I show these galaxies have significant Mg-enhancement which cannot be explained solely by short formation timescale as proposed by simple chemical evolution models, then I discuss new scenarios to explain chemical abundances in these galaxies.