Astronomy and Astrophysics – Astronomy
Scientific paper
Jan 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993egte.conf..313p&link_type=abstract
In NASA. Ames Research Center, The Evolution of Galaxies and Their Environment p 313-314 (SEE N93-26706 10-90)
Astronomy and Astrophysics
Astronomy
Accretion Disks, Active Galactic Nuclei, Blazars, Data Bases, Iue, Seyfert Galaxies, Sky Surveys (Astronomy), Ultraviolet Spectra, Algorithms, Continuums, Exosat Satellite, Infrared Astronomy Satellite, Luminosity, Red Shift, Statistical Tests, Thermal Emission
Scientific paper
In 13 years of operation, IUE has gathered approximately 5000 spectra of almost 600 Active Galactic Nuclei (AGN). In order to undertake AGN studies which require large amounts of data, we are consistently reducing this entire archive and creating a homogeneous, easy-to-use database. First, the spectra are extracted using the Optimal extraction algorithm. Continuum fluxes are then measured across predefined bands, and line fluxes are measured with a multi-component fit. These results, along with source information such as redshifts and positions, are placed in the IUEAGN relational database. Analysis algorithms, statistical tests, and plotting packages run within the structure, and this flexible database can accommodate future data when they are released. This archival approach has already been used to survey line and continuum variability in six bright Seyfert 1s and rapid continuum variability in 14 blazars. Among the results that could only be obtained using a large archival study is evidence that blazars show a positive correlation between degree of variability and apparent luminosity, while Seyfert 1s show an anti-correlation. This suggests that beaming dominates the ultraviolet properties for blazars, while thermal emission from an accretion disk dominates for Seyfert 1s. Our future plans include a survey of line ratios in Seyfert 1s, to be fitted with photoionization models to test the models and determine the range of temperatures, densities and ionization parameters. We will also include data from IRAS, Einstein, EXOSAT, and ground-based telescopes to measure multi-wavelength correlations and broadband spectral energy distributions.
Edelson Richard
Pike G.
Saken Jon
Shull Michael J.
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