REST-UV ABSORPTION LINES AS METALLICITY ESTIMATOR: THE METAL CONTENT OF STAR-FORMING GALAXIES AT z ∼ 5

• Published in: The Astrophysical journal 2016-05, Vol.822 (1), p.29-29
• Main Authors: Faisst, A. L., Capak, P. L., Davidzon, I., Salvato, M., Laigle, C., Ilbert, O., Onodera, M., Hasinger, G., Kakazu, Y., Masters, D., McCracken, H. J., Mobasher, B., Sanders, D., Silverman, J. D., Yan, L., Scoville, N. Z.
• Format: Article
• Language: English
• Subjects: ABSORPTION; Accumulation; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; COSMIC DUST; EMISSION; GALACTIC EVOLUTION; Galaxies; galaxies: abundances; galaxies: evolution; galaxies: high redshift; galaxies: ISM; MARINE SURVEYS; MASS; METALLICITY; RED SHIFT; STAR EVOLUTION; Star formation; STARS; Stellar mass; STOCHASTIC PROCESSES; ULTRAVIOLET SPECTRA; UNIVERSE
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/822/1/29

ABSTRACT We measure a relation between the depth of four prominent rest-UV absorption complexes and metallicity for local galaxies and verify it up to . We then apply this relation to a sample of 224 galaxies at ( ) in the Cosmic Evolution Survey (COSMOS), for which unique UV spectra from the Deep Imaging Multi-object Spectrograph (DEIMOS) and accurate stellar masses from the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH) are available. The average galaxy population at and is characterized by 0.3-0.4 dex (in units of ) lower metallicities than at z ∼ 2, but comparable to . We find galaxies with weak or no Ly emission to have metallicities comparable to z ∼ 2 galaxies and therefore may represent an evolved subpopulation of galaxies. We find a correlation between metallicity and dust in good agreement with local galaxies and an inverse trend between metallicity and star-formation rate consistent with observations at z ∼ 2. The relation between stellar mass and metallicity (MZ relation) is similar to , but there are indications of it being slightly shallower, in particular for the young, Ly -emitting galaxies. We show that, within a "bathtub" approach, a shallower MZ relation is expected in the case of a fast (exponential) build-up of stellar mass with an e-folding time of 100-200 Myr. Because of this fast evolution, the process of dust production and metal enrichment as a function of mass could be more stochastic in the first billion years of galaxy formation compared to later times.