Absolute Spectral Energy Distribution of Quasi-Stellar Objects from 0.3 to 2.2 Microns

Abstract

The absolute spectral energy distribution from 0.32 to 2.2 μ, has been obtained for twenty-eight quasi-stellar sources. Photometry at 2.2 μ, has been obtained for an additional fifteen objects. The data show that the continua over this wavelength range generally can be described with a power-law spectrum; the index varies from -0.2 to -1.6, with the entire range being populated. For quasi-stellar objects which are known to have large-amplitude variations in visual magnitude, the energy distributions remain sensibly unchanged during the variations. No characteristic of the energy distribution in the observed range of wavelengths which distinguishes between radio-quiet and radio-active quasi-stellar objects is found. The near constancy of the observed ratio of the line intensities of Lɑ to the C IV line can be interpreted as implying an electron temperature of 20000° K. The range of equivalent widths of both (Hɑ + [N II]) and Lɑ is small. The ratio of the number of photons in the Lyman continuum with respect to the number in the Lɑ line is not consistent with radiative recombination from an opaque source.

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