2006/10/27 by Benjamin J. Weiner, Casey Papovich, K. Bundy +7 · 3 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Emission spectrum #Extinction (optical mineralogy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Line (geometry) #Luminosity #Luminous infrared galaxy #Star formation #astro-ph
paper · pdf · doi:10.1086/517925
published as Astrophys.J.660:L39-L42,2007 · 4 pages, 3 figures. Accepted for publication in ApJ Letters AEGIS special edition
arxiv created 2006/10/27 · openalex publication_date 2007/04/04 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Strong nebular emission lines are a sensitive probe of star formation and extinction in galaxies, and the [O II] line detects star-forming populations out to z > 1. However, star formation rates from emission lines depend on calibration of extinction and the [O II]/Hα line ratio, and separating star formation from AGN emission. We use calibrated line luminosities from the DEEP2 survey and Palomar K magnitudes to show that the behavior of emission-line ratios depends on galaxy magnitude and color. For galaxies on the blue side of the color bimodality, the vast majority show emission signatures of star formation, and there are strong correlations of extinction and [O II]/Hα with rest-frame H magnitude. The conversion of [O II] to extinction-corrected Hα and thus to star formation rate has a significant slope with M H , 0.23 dex mag -1 . Red galaxies with emission lines have a much higher scatter in their line ratios, and more than half show AGN signatures. We use 24 μm fluxes from Spitzer MIPS to demonstrate the differing populations probed by nebular emission and by mid-IR luminosity. Although extinction is correlated with luminosity, 98% of IR-luminous galaxies at z ~ 1 are still detected in the [O II] line. Mid-IR-detected galaxies are mostly bright and intermediate color, while fainter, bluer galaxies with high [O II] luminosity are rarely detected at 24 μm.