2015/02/28 by Debopam Som, Varsha P. Kulkarni, Joseph Meiring +5
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Chemical evolution #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Galaxy merger #Interacting galaxy #Lenticular galaxy #Protogalaxy #Space (punctuation) #Type-cD galaxy #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1088/0004-637x/806/1/25
77 pages, 13 figures; accepted for publication in the Astrophysical Journal. Submitted (in the original form) May 26, 2014; accepted Apr. 15, 2015
arxiv created 2015/05/10 · openalex publication_date 2015/06/05 · arxiv updated 2015/06/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We report observations of four sub-damped Ly α (sub-DLA) quasar absorbers at obtained with the Hubble Space Telescope Cosmic Origins Spectrograph. We measure the available neutrals or ions of C, N, O, Si, P, S, Ar, Mn, Fe, and/or Ni. Our data have doubled the sub-DLA metallicity samples at and improved constraints on sub-DLA chemical evolution. All four of our sub-DLAs are consistent with near-solar or super-solar metallicities and relatively modest ionization corrections; observations of more lines and detailed modeling will help to verify this. Combining our data with measurements from the literature, we confirm previous suggestions that the N(H i )-weighted mean metallicity of sub-DLAs exceeds that of DLAs at all redshifts studied, even after making ionization corrections for sub-DLAs. The absorber toward PHL 1598 shows significant dust depletion. The absorbers toward PHL 1226 and PKS 0439-433 show the S/P ratio consistent with solar, i.e., they lack a profound odd–even effect. The absorber toward Q0439-433 shows super-solar Mn/Fe. For several sub-DLAs at , [N/S] is below the level expected for secondary N production, suggesting a delay in the release of the secondary N or a tertiary N production mechanism. We constrain the electron density using Si ii * and C ii * absorption. We also report different metallicity versus relations for sub-DLAs and DLAs. For two sub-DLAs with detections of emission lines from the underlying galaxies, our measurements of the absorption-line metallicities are consistent with the emission-line metallicities, suggesting that metallicity gradients are not significant in these galaxies.