TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry - II. Additional Sources

Abstract

TANAMI is a multiwavelength program monitoring active galactic nuclei (AGN) south of -30deg declination including high-resolution Very Long Baseline Interferometry (VLBI) imaging, radio, optical/UV, X-ray and gamma-ray studies. We have previously published first-epoch 8.4GHz VLBI images of the parsec-scale structure of the initial sample. In this paper, we present images of 39 additional sources. The full sample comprises most of the radio- and gamma-ray brightest AGN in the southern quarter of the sky, overlapping with the region from which high-energy (>100TeV) neutrino events have been found. We characterize the parsec-scale radio properties of the jets and compare with the quasi-simultaneous Fermi/LAT gamma-ray data. Furthermore, we study the jet properties of sources which are in positional coincidence with high-energy neutrino events as compared to the full sample. We test the positional agreement of high-energy neutrino events with various AGN samples. Our observations yield the first images of many jets below -30deg declination at milliarcsecond resolution. We find that gamma-ray loud TANAMI sources tend to be more compact on parsec-scales and have higher core brightness temperatures than gamma-ray faint jets, indicating higher Doppler factors. No significant structural difference is found between sources in positional coincidence with high-energy neutrino events and other TANAMI jets. The 22 gamma-ray brightest AGN in the TANAMI sky show only a weak positional agreement with high-energy neutrinos demonstrating that the >100TeV IceCube signal is not simply dominated by a small number of the $\gamma$-ray brightest blazars. Instead, a larger number of sources have to contribute to the signal with each individual source having only a small Poisson probability for producing an event in multi-year integrations of current neutrino detectors.

arXiv commentA&A accepted (edited version), 21 pages, 13 figures

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Cited by in corpus (9)

• Gamma-ray emission in radio galaxies under the VLBI scope -- I. Parsec-scale kinematics and high-energy properties of $\gamma$-ray detected TANAMI radio galaxies
• Fermi-LAT counterparts of IceCube neutrinos above 100 TeV
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• The 1.4 mm core of Centaurus A: First VLBI results with the South Pole Telescope
• Gamma-ray flares and broadband spectral study of PKS 0402-362
• Multi-frequency Variability Study of Flat-Spectrum Radio Quasar PKS 0346-27
• TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry. III. First-epoch S band images
• Gamma-ray emission in radio galaxies under the VLBI scope -- II. The relationship between gamma-ray emission and parsec-scale jets in radio galaxies
• VLTI-GRAVITY observations of blazars