Radio Continuum Survey of an Optically Selected Sample of Nearby Seyfert Galaxies

By Luis C. Ho, J. Ulvestad. 2001

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We have used the Very Large Array (VLA) to conduct a survey for radio continuum emission in the sample of 52 Seyfert nuclei selected from the optical spectroscopic galaxy catalog of Ho, Filippenko, & Sargent. This Seyfert sample is the most complete and least biased available, and, as such, it will be useful for a variety of statistical analyses. Here we present the observations, measurements, and an atlas of radio maps. The observations were made at 6 cm in the B array and at 20 cm in the A array, yielding matched angular resolutions of ~1''. We detected 44 objects (85%) at 6 cm and 37 objects (71%) at 20 cm above a 3 σ threshold of 0.12 mJy beam-1. The sources have a wide range of radio powers (P ≈ 1018-1025 W Hz-1), spectral indices (α ≈ +0.5 to -1), and linear sizes (L ≈ few tens pc-15 kpc). The morphology of the radio emission is predominantly that of a compact core, either unresolved or slightly resolved, occasionally accompanied by elongated, jetlike features. Linearly polarized emission was detected at 6 cm in 12 sources, nine of which were also detected at 20 cm.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

Nuclear Activity in Nearby Galaxies (2008, methodology): “…of a self-respecting AGN: broad optical and UV emission lines (Filippenko & Sargent 1989; Filippenko, Ho & Sargent 1993), a compact radio core (Ho & Ulvestad 2001) of high brightness temperature (Wrobel, Fassnacht & Ho 2001; Wrobel & Ho 2006), and rapidly variable hard X-ray emission (Shih,…”
On the origin of radio emission in radio-quiet quasars (2008, methodology): “Systematic analysis of radio (Ho & Ulvestad 2001) and X-ray (Panessa et al. 2006) observations is available for all 12 objects.”
Radio sources in low-luminosity active galactic nuclei IV. Radio luminosity function, importance of jet power, and radio properties of the complete Palomar sample (2005, background): “Of the 14 type 1 nuclei not detected in our radio survey, all 5 Seyferts were found to have radio nuclei in the deeper radio survey of Ho & Ulvestad (2001), while the nature of the others is unknown.”
X-Ray Properties of LINERs and Low-Luminosity Seyfert Galaxies Observed with ASCA. I. Observations and Results (2002, background): “Finally, the radio properties further support the AGN interpretation: the nucle s contains a compact radio core which has a flat spectrum (Nagar et al. 2000; Falcke et al. 2000) and is variable (Falcke et al. 2001; Ho & Ulvestad 2001).”
On the X-ray, optical emission line and black hole mass properties of local Seyfert galaxies ! (2006, methodology): “A radio core is detected (Ho & Ulvestad 2001).”
X-ray spectral survey with XMM-Newton of a complete sample of nearby Seyfert galaxies (2005, methodology): “The sample studied in this paper is drawn from 52 nearby Seyfert galaxies given in HFS97a (see also Ho & Ulvestad 2001, HU01 hereinafter).”
On the Relationship between Radio Emission and Black Hole Mass in Galactic Nuclei (2001, background): “@) wavelengths other than 6 cm, and these were extrapolated to 6 cm assuming the median spectrum betweenfl P l~0.5,6 and 20 cm for Seyfert nuclei found by Ho & Ulvestad (2001).”
A Hubble Space Telescope Survey of Extended [O III] λ5007 Emission in a Far-Infrared Selected Sample of Seyfert Galaxies: Observations (2003, result): “During recent years, several papers have presented results which seem to contradict the model predictions, but most of these can be explained as due to selection effects (see Schmitt et al. 2001a; Ho & Ulvestad 2001 for a more detailed discussion).”
A Fundamental plane of black hole activity (2003, background): “Flat spectrum LLAGN were originally selected in the optical band, from the Palomar spectroscopic survey (Ho, Filippenko, & Sargent 1997a).”
Nuclear Luminosities and Radio Loudness of Seyfert Nuclei (2001, methodology): “As discussed by Ho et al. (1997b) and Ho & Ulvestad (2001), the Palomar Seyfert sample is the most complete and least biased available.”
A Survey of Kiloparsec-Scale Radio Outflows in Radio-Quiet Active Galactic Nuclei (2006, background): “The central radio source is unresolved by long-baseline VLA and MERLIN observations (Ulvestad & Wilson 1984b; Kukula et al. 1995; Ho & Ulvestad 2001; Thean et al. 2001b).”
A Search for “Dwarf” Seyfert Nuclei. VI. Properties of Emission-Line Nuclei in Nearby Galaxies (2002, background): “In this respect, the Palomar surveyhas a number of merits, as emphasized by Ho & Ulvestad (2001).”