Matching Items (2)
Description
The first part of this dissertation presents the implementation of Bayesian statistics with galaxy surface luminosity (SL) prior probabilities to improve the ac- curacy of photometric redshifts. The addition of the SL prior probability helps break the degeneracy of spectro-photometric redshifts (SPZs) between low redshift 4000 A break galaxies and high redshift Lyman break galaxies which are mostly catas- trophic outliers. For a sample of 1138 galaxies with spectroscopic redshifts in the GOODS North and South fields at z < 1.6, the application of the surface luminosity prior reduces the fraction of galaxies with redshift deviation sigma(z) > 0.2 from 15.0% to 10.4%. The second part of this dissertation presents the study of the chemical evolution of the star-forming galaxies. The Hubble Space Telescope Probing Evolution and Reionization Spectroscopically (PEARS) grism Survey effectively selects emission line galaxies (ELGs) to mAB ~ 27. Follow-up Magellan LDSS3+IMACS spectroscopy of the HST/ACS PEARS ELGs confirms an accuracy of sigma_z = 0.006 for the HST/ACS PEARS grism redshifts. The luminosity-metallicity (L-Z) relation and the mass-metallicity (M-Z) relation of the PEARS ELGs at z ~ 0.6 are offset by ~ - 0.8 dex in metallicity for a given rest-frame B absolute magnitude and stellar mass relative to the local relations from SDSS galaxies. The offsets in both relations are ~ - 0.4 dex larger than that given by other samples at same redshifts, which are demonstrated to be due to the selection of different physical properties of the PEARS ELGs: low metallicities, very blue colors, small sizes, compact disturbed morphologies, high SSFR > 10^-9 yr^-1 , and high gas fraction. The downsizing effect, the tidal interacting induced inflow of metal-poor gas, and the SNe driven galactic winds outflows, may account for the significant offset of the PEARS galaxies in the L-Z and the M-Z relations relative to the local relations. The detection of the emission lines of ELGs down to m ~ 26 mag in the HST/ACS PEARS + HST/WCF3 ERS NIR composit grism spectra enables to extend the study of the evolution of the L-Z and M-Z relations to 0.6 < z < 2.4.
ContributorsXia, Lifang (Author) / Malhotra, Sangeeta (Thesis advisor) / Rhoads, James (Committee member) / Scannapieco, Evan (Committee member) / Jansen, Rolf (Committee member) / Young, Patrick (Committee member) / Arizona State University (Publisher)
Created2012
Description
The interaction induced chiral asymmetry is calculated in cold QED plasma beyond the weak-field approximation. By making use of the recently developed Landau-level representation for the fermion self-energy, the chiral shift and the parity-even chiral chemical potential function are obtained with the help of numerical methods. The results are used to quantify the chiral asymmetry of the Fermi surface in dense QED matter. Because of the weakness of the QED interactions, the value of the asymmetry appears to be rather small even in the strongest magnetic fields and at the highest stellar densities. However, the analogous asymmetry can be substantial in the case of dense quark matter.
ContributorsXia, Lifang (Author) / Gorbar, E. V. (Author) / Miransky, V. A. (Author) / Shovkovy, Igor (Author) / College of Liberal Arts and Sciences (Contributor)
Created2014-10-10