A Multifrequency Study of Optically Quiet Quasars

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Session 19 -- Multiwavelength AGN Studies
Display presentation, Monday, 9, 1995, 9:20am - 6:30pm

[19.08] A Multifrequency Study of Optically Quiet Quasars

R. I. Kollgaard, E. D. Feigelson, S. A. Laurent-Muehleisen (Penn State University), H. Spinrad, A. Dey (University of Calififornia), W. Brinkmann (MPIfEP)

Optically Quiet Quasars (OQQs), also known as Red Quasars, are compact radio-loud and X-ray bright active galactic nuclei with very weak optical continuum emission. Several explanations have been proposed for the inverted spectral energy distribution of OQQs (SEDs with $C \equiv \alpha_{{\rm ro}} / \alpha_{{\rm ox}} > 1$), in particular excess reddening and soft X-ray absorption over that expected from the Galaxy. We have made multifrequency observations of three previously known OQQs: 0026+346 a GHz-peaked galaxy at $z=0.6$, 0406+121 a BL~Lac object at $z=1.02$, and 0500+019 a GHz-peaked radio source with an unknown redshift. ROSAT PSPC spectra are consistent with excess absorption, although we cannot rule out a purely galactic $N_H$ if the X-ray spectra are very hard. New optical observations of 0406+121 and 0500+019 confirm the steep optical continuum. The wide range of radio and optical properties of OQQs suggests that, if excess absorption is important, it arises from a physically unrelated system that intercepts the line of sight. Gravitational microlensing from an intervening system may also explain some of the extreme properties in 0406+121 and other ``red blazars''.

We also observed 10 OQQ candidates selected from two correlations of the ROSAT all-sky survey (RASS) with radio surveys. A few AGNs with $C \sim 1$, but no clear examples of true OQQs, indicating that inverted SEDs are rare.

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