Falcke et al., Boosted Radio-Weak Quasars

EVN+MERLIN Observations of Radio-Intermediate Quasars: Evidence for Boosted Radio-Reak Quasars

Heino Falcke(1), Alok Patnaik(2), William Sherwood(2)

(1) Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (hfalcke@astro.umd.edu)
(2) Max-Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
(apatnai@mpifr-bonn.mpg.de, wsherwood@mpifr-bonn.mpg.de)

The Astrophysical Journal Letters, Vol. 473, L13-L16


We present VLBI (EVN+MERLIN) observations of a sample of three low-redshift radio-intermediate PG quasars (RIQ) with flat and variable radio spectrum (III Zw 2, PG 1309+355, PG 2209+184). Their radio-to-optical flux ratio (R) is slightly lower than the average R for steep-spectrum quasars, but their radio spectral properties are those of core-dominated quasars. It was proposed previously that these sources might be relativistically boosted jets in radio-weak quasars. Our VLBI observations now indeed confirm the presence of a high brightness temperature core in all three of these objects --- two of them have lower limits on TB well in excess of 1010 Kelvin. Moreover, we find no ``missing-flux'' which means that basically all the flux of these quasars is concentrated in the compact radio core. As the total radio flux is already at the low end for radio-loud quasars, we can place a strong limit on the presence of any extended emission. This limit is consistent with the extended emission in radio-weak quasars, but excludes that the flat-spectrum RIQ reside in typical radio-loud quasars. The observations therefore strongly support the idea that relativistic jets are present in radio-weak quasars and hence that radio-loud and radio-weak quasars have very similar central engines.

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Paper: Available in full length after acceptance as PostScript and LaTex (AAS) Format.

Other publications can be found here.

Questions: Heino Falcke, hfalcke@mpifr-bonn.mpg.de