Active Nuclei and Star-forming Objects at [ITAL][CLC]z[/CLC][/ITAL] ] 2: Metallicities, Winds, and Formation Histories

摘要: We present near-infrared observations of the active galactic nuclei (AGNs) and star-forming objects in field radio galaxy 53W002 at z = 2.39. The are special interest as candidate protogalactic objects. 1.1–2.2 μm passbands sample emitted-optical range this redshift, providing new diagnostics structure, metal abundance, age members grouping originally selected through Lyα emission. uniformly very blue continuum slope, which fits with strong emission indicating abundances that less than half solar; some most metal-poor local They fall a luminosity metallicity is not populated by objects, shorter history early epoch. best analogs, such Mrk 66 357, either have several times lower comparable [O/H] or significantly higher for luminosity. Spectroscopy from Near-Infrared Camera Multi-Object Spectrometer yields detections [O III] two interesting Hβ limits rest, augmented Hα Infrared Telescope Facility imaging. These data satisfied model stellar populations been forming stars last 2–5 × 106 yr before do see evidence older preexisting populations, broadband colors redder halos regions imbedded. results suggest compact we 2.0–2.5 indeed stages building galaxies rather transient events larger pre-existing dynamical systems. also allow an alternative scheme, these low-mass systems blowing winds self-enriching, case they should fade rapidly cosmic For three prominent AGNs 2.39, were measured. Unlike fainter their line ratios (specifically Lyα/Hα) show metallicities just high nearby If occur those started highest density began star formation massive surrounding will (as emitted-ultraviolet ratios). "ionization cones" seen prominently appear Hα, role reflection cases well. contrast between can be broadly accommodated hierarchical picture, although there still important unknowns to fate