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  • ASTROPHYSICS  (3)
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  • 1
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    The Lyman edge test of the quasar emission mechanism (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The Lyman edge region in the spectra of 11 high-redshift quasars is studied using data designed to detect broadened Lyman edge absorption predicted by thermal models of the 'big blue bump' continuum component, especially thin accretion disks. Three objects have broadened, partial edges near the systemic redshifts, as expected for thermal models. In two cases, however, narrow Lyamn lines with the edge absorption, ruling out the disk interpretation. Thus, the data are negative for thermal models, at least for opaque thin accretion disks.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 342; 64-82
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    FOS spectroscopy of resolved structure in the nucleus of NGC 1068 (1991)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The results of FOS spectroscopy of the continuum peak of NGC 1068 in the wavelength range 2200-7000 A are reported. Detailed analysis reveals the emission lines to be complex in shape and to consist of a number of different velocity components. Both the Balmer lines and the strong forbidden lines have a contribution from a component with full width at half-maximum on the order of 2200 km/s. However, the broad H-beta emission observed in polarized light is not detected. This implies that the continuum peak is not the mirror which reflects light from the hidden Seyfert I nucleus. It could possibly contribute some of the reflected light, but the equivalent width of the H-beta BLR line, if present at all, is much weaker than expected from the ground-based nuclear polarized-flux spectrum.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 377; L9-L12
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    The featureless continua and hydrogen lines of Seyfert 2 galaxies (1991)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Optical and ultraviolet spectra taken in similar sized large apertures for 15 Seyfert 2 galaxies are presented. Measurements of emission-line strengths of Ly-alpha, H-alpha, and H-beta are used together with measurements of the ultraviolet slopes to estimate the ratio of recombination photons to ionizing photons. The photon ratios indicate that the ionizing continuum is being emitted anisotropically for at least six of the eight objects with UV slope measurements. The median value of the UV slope is indistinguishable from the UV slope of Seyfert 1 galaxies. This result suggests that in the occultation/reflection picture of Seyfert nuclei, the reflecting particles are free electrons and not dust. Previous observations of variability in Mrk 477 are verified, and it is shown that this galaxy exhibits characteristics of both Seyfert 1 and Seyfert 2 galaxies.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 377; 100-114
    Format: text
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