A deep, high resolution survey of the low frequency radio sky

ApJ 673 (2008) 78

DOI: 10.1086/524295 (http) or 10.1086/524295 (doi)
ADS bibcode 2008ApJ...673...78L
arXiv:0710.1946

E. Lenc [1], M.A. Garrett [2], O. Wucknitz [3,4], J.M. Anderson [3], S.J. Tingay [5]

  1. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Mail number H39, P.O. Box 218, Hawthorn, Victoria 3122, Australia
  2. Netherlands Foundation for Research in Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo, The Netherlands
  3. Joint Institute for VLBI in Europe, Postbus 2, 7990 AA Dwingeloo, The Netherlands
  4. Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
  5. Department of Imaging and Applied Physics, Curtin University of Technology, Bentley 6845, Western Australia, Australia

Abstract

We report on the first wide-field, very long baseline interferometry (VLBI) survey at 90 cm. The survey area consists of two overlapping 28 sq-deg fields centred on the quasar J0226+3421 and the gravitational lens B0218+357. A total of 618 sources were targeted in these fields, based on identifications from Westerbork Northern Sky Survey (WENSS) data. Of these sources, 272 had flux densities that, if unresolved, would fall above the sensitivity limit of the VLBI observations. A total of 27 sources were detected as far as 2deg from the phase centre. The results of the survey suggest that at least 10% of moderately faint (S ca 100 mJy) sources found at 90 cm contain compact components smaller than ca 0.1 to 0.3 arcsec and stronger than 10% of their total flux densities. A ca 90 mJy source was detected in the VLBI data that was not seen in the WENSS and NRAO VLA Sky Survey (NVSS) data and may be a transient or highly variable source that has been serendipitously detected. This survey is the first systematic (and non-biased), deep, highresolution survey of the low-frequency radio sky. It is also the widest field of view VLBI survey with a single pointing to date, exceeding the total survey area of previous higher frequency surveys by two orders of magnitude. These initial results suggest that new low frequency telescopes, such as LOFAR, should detect many compact radio sources and that plans to extend these arrays to baselines of several thousand kilometres are warranted.

Key words: galaxies: active - quasars: individual (B0218+357, J0226+3421) - techniques: interferometry - radiation mechanisms: general

For a poster presentation of early results, click here. Reduced-size version available on the preprint server.


ApJ 673 (2008) 78 (link to online journal)
DOI (Digital Object Identifier): 10.1086/524295 (http) or 10.1086/524295 (doi)
ADS bibcode 2008ApJ...673...78L (link to ADS entry)
arXiv:0710.1946 (link to e-print archive)


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