The Long Baseline Array

Edwards, P. G.; Phillips, Chris

doi:10.5303/pkas.2015.30.2.659

Cited by 10 publications

(14 citation statements)

References 23 publications

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“…The southernmost four GPS candidates were observed with the Australian Long Baseline Array (Edwards & Phillips 2015) Table 1 GPS candidates from Edwards & Tingay (2004). Flux density at 4.8 GHz, S 5 , variability index at 4.8 GHz, M 5 , fractional polarisation at 4.8 GHz, p 5 , and peak frequency ν pk , are reproduced from Edwards & Tingay (2004).…”

Section: Lba Observationsmentioning

confidence: 98%

The Parsec-Scale Morphology of Southern GPS Sources

Edwards

Tingay

2016

Publ. Astron. Soc. Aust.

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Multi-frequency, multi-epoch ATCA observations of a sample of AGN resulted in the identification of 9 new candidate Giga-hertz Peaked Spectrum (GPS) sources. Here we present Long Baseline Array observations at 4.8 GHz of the four candidates with no previously published VLBI image, and consider these together with previously published VLBI images of the other five sources. We find core-jet or compact double morphologies dominate, with further observations required to distinguish between these two possibilities for some sources. One of the nine candidates, PKS 1831−711, displays appreciable variability, suggesting its GPS spectrum is more ephemeral in nature. We focus in particular on the apparent relationship between a narrow spectral width and "compact double" parsec-scale morphology, finding further examples, but also exceptions to this trend. An examination of the VLBI morphologies high-redshift (z >3) sub-class of GPS sources suggests that core-jet morphologies predominate in this class.

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Section: Lba Observationsmentioning

confidence: 98%

The Parsec-Scale Morphology of Southern GPS Sources

Edwards

Tingay

2016

Publ. Astron. Soc. Aust.

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“…TANAMI VLBI observations are made at 8.4 GHz and 22 GHz using antennas that constitute the Australian Long Baseline Array (Edwards & Phillips 2015), augmented by those at Hartebeesthoek (South Africa), TIGO (Chile 3 ), O'Higgins (Antarctica), NASA Deep Space Network antennas at Tidbinbilla (Australia), as well as the Auscope telescopes at Katherine and Yarragadee (both Australia; Lovell et al 2013), and Warkworth (New Zealand;Weston et al 2013). Telescope information is listed in Table 1.…”

Section: Sample Observations and Data Reductionmentioning

confidence: 99%

TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry

Müller

Kadler

Ojha

et al. 2018

A&A

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Context. TANAMI is a multiwavelength program monitoring active galactic nuclei (AGN) south of − 30° declination including high-resolution very long baseline interferometry (VLBI) imaging, radio, optical/UV, X-ray, and γ-ray studies. We have previously published first-epoch8.4 GHz 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 γ-ray brightest AGN in the southern quarter of the sky, overlapping with the region from which high-energy (> 100 TeV) neutrino events have been found. Aims. We characterize the parsec-scale radio properties of the jets and compare them with the quasi-simultaneous Fermi/LAT γ-ray data. Furthermore, we study the jet properties of sources which are in positional coincidence with high-energy neutrino events compared to the full sample. We test the positional agreement of high-energy neutrino events with various AGN samples. Methods. TANAMI VLBI observations at 8.4 GHz are made with southern hemisphere radio telescopes located in Australia, Antarctica, Chile, New Zealand, and South Africa. Results. Our observations yield the first images of many jets below − 30° declination at milliarcsecond resolution. We find that γ-ray loud TANAMI sources tend to be more compact on parsec-scales and have higher core brightness temperatures than γ-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 γ-ray brightest AGN in the TANAMI sky show only a weak positional agreement with high-energy neutrinos demonstrating that the > 100 TeV IceCube signal is not simply dominated by a small number of the γ-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.

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“…The LBA observations presented here, of five high-confidence EGRET identifications and five of the more probable ‘plausible’ identifications, enable us to examine the source morphology and study radio properties including core brightness temperature and core dominance. The observations were conducted with the LBA (Edwards & Phillips 2015) over a period of 24 h commencing on 2001 November 10 under the observation code V151. The telescopes participating in the observations were Ceduna 30 m (System Equivalent Flux Density (SEFD) 450 Jy), Hartebeesthoek 26 m (SEFD 290 Jy), Hobart 26 m (SEFD 640 Jy), Mopra 22 m (SEFD 350 Jy), Parkes 64 m (SEFD 110 Jy), and a ‘tied array’ of 5 × 22 m antennas of the Australia Telescope Compact Array (SEFD 70 Jy).…”

Section: Observationsmentioning

confidence: 99%

VLBI Observations of Southern Gamma-Ray Sources. III

Edwards

Ojha

Dodson

et al. 2018

Publ. Astron. Soc. Aust.

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We report the results of Long Baseline Array observations made in 2001 of ten southern sources proposed by Mattox et al. as counterparts to EGRET >100 MeV gamma-ray sources. Source structures are compared with published data where available and possible superluminal motions identified in several cases. The associations are examined in the light of Fermi observations, indicating that the confirmed counterparts tend to have radio properties consistent with other identifications, including flat radio spectral index, high brightness temperature, greater radio variability, and higher core dominance.

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The Long Baseline Array

Cited by 10 publications

References 23 publications

The Parsec-Scale Morphology of Southern GPS Sources

The Parsec-Scale Morphology of Southern GPS Sources

TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry

VLBI Observations of Southern Gamma-Ray Sources. III

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