The VLBA CANDELS GOODS-North Survey -I. survey design, processing, data products, and source counts
Journal article, 2024
The past decade has seen significant advances in wide-field cm-wave very long baseline interferometry (VLBI), which is timely given the wide-area, synoptic survey-driven strategy of major facilities across the electromagnetic spectrum. While wide-field VLBI poses significant post-processing challenges that can severely curtail its potential scientific yield, man y dev elopments in the km-scale connected-element interferometer sphere are directly applicable to addressing these. Here we present the design, processing, data products, and source counts from a deep (11 μJy beam -1 ), quasi-uniform sensitivity, contiguous wide-field (160 arcmin 2 ) 1.6 GHz VLBI surv e y of the CANDELS GOODS-North field. This is one of the best-studied extragalactic fields at milli-arcsecond resolution and, therefore, is well-suited as a comparative study for our Tera-pixel VLBI image. The derived VLBI source counts show consistency with those measured in the COSMOS field, which broadly traces the AGN population detected in arcsecond-scale radio surv e ys. Ho we ver, there is a distinctive flattening in the S 1.4GHz ∼100-500 μJy flux density range, which suggests a transition in the population of compact faint radio sources, qualitatively consistent with the excess source counts at 15 GHz that is argued to be an unmodelled population of radio cores. This surv e y approach will assist in deriving robust VLBI source counts and broadening the disco v ery space for future wide-field VLBI surv e ys, including VLBI with the Square Kilometre Array, which will include new large field-of-view antennas on the African continent at ≲1000 km baselines. In addition, it may be useful in the design of both monitoring and/or rapidly triggered VLBI transient programmes.
galaxies: active
techniques: interferometric
techniques: high angular resolution
Author
R. P. Deane
University of Witwatersrand
University of Pretoria
Jack F. Radcliffe
University of Manchester
University of Pretoria
Ann Njeri
University of Manchester
Newcastle University
Alexander Akoto-Danso
Ghana Atomic Energy Commission
Rhodes University
Gianni Bernardi
Rhodes University
South African Radio Astronomy Observatory (SARAO)
Istituto di Radioastronomia
O. Smirnov
Rhodes University
South African Radio Astronomy Observatory (SARAO)
R. J. Beswick
University of Manchester
Michael A. Garrett
University of Manchester
Leiden University
M.J. Jarvis
University of the Western Cape
University of Oxford
Imogen H. Whittam
University of the Western Cape
University of Oxford
Stephen Bourke
Chalmers, Space, Earth and Environment, Onsala Space Observatory
Overstock Ireland Ltd
Z. Paragi
Joint Institute for VLBI in Europe (JIVE)
Monthly Notices of the Royal Astronomical Society
00358711 (ISSN) 13652966 (eISSN)
Vol. 529 3 2428-2442Subject Categories
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
Other Physics Topics
DOI
10.1093/mnras/stae253