Open AccessEmission‐line abundances of absorption‐selected galaxies at z < 0.5
Author(s) -
Ellison Sara L.,
Kewley Lisa J.,
MallénOrnelas Gabriela
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.08674.x
Subject(s) - physics , astrophysics , redshift , galaxy , luminosity , metallicity , luminous infrared galaxy , emission spectrum , line (geometry) , spectral line , astronomy , geometry , mathematics
We have obtained optical spectra of four galaxies associated with Mg ii quasi‐stellar object (QSO) absorbers at redshifts 0.10 < z < 0.45 . We calculate the gas‐phase oxygen abundance of these galaxies using the empirical R 23 strong‐line method. The absolute B ‐band magnitudes of the galaxies span −20.6 < M B < −18.3 . If the metallicities lie on the R 23 upper branch (8.4 < log (O/H) + 12 < 8.9) , then the metallicities of these absorption‐selected galaxies span the range between 0.5 and 1.4 Z ⊙ and would be consistent with the well‐known luminosity–metallicity relation for 0.10 < z < 0.45 emission‐line galaxies. However, such metallicities would be 0.5–1.0 dex higher than those observed in damped Lyman α systems (DLAs) via absorption‐line measurements at similar redshifts. Conversely, the lower R 23 branch calibration yields metallicities Z ∼ 1/7 Z ⊙ , consistent with the DLA absorption metallicities at low redshifts. In this case, the absorption‐selected galaxies would lie significantly lower than the luminosity–metallicity relation for emission‐line galaxies at z < 0.5 . We discuss the implications and possible solutions for each scenario.