Faint Radio Sources in the NOAO Bootes Field. VLBA Imaging And Optical Identifications

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As a step toward investigating the parsec-scale properties of faint extragalactic radio sources, the Very Long Baseline Array (VLBA) was used at 5.0 GHz to obtain phase-referenced images of 76 sources in the NOAO Booetes field. These 76 sources were selected from the FIRST catalog to have peak flux densities above 10 mJy at 5'' resolution and deconvolved major diameters of less than 3'' at 1.4 GHz. Fifty-five of these faint radio sources were identified with accretion-powered radio galaxies and quasars brighter than 25.5 mag in the optical I band. On VLA scales at 1.4 GHz, a measure of the ... continued below

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30 pages

Creation Information

Wrobel, J.M.; /NRAO, Socorro; Taylor, Greg B.; /NRAO, Socorro /KIPAC, Menlo Park; Rector, T.A.; /NRAO, Socorro /Alaska U. et al. June 13, 2005.

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Description

As a step toward investigating the parsec-scale properties of faint extragalactic radio sources, the Very Long Baseline Array (VLBA) was used at 5.0 GHz to obtain phase-referenced images of 76 sources in the NOAO Booetes field. These 76 sources were selected from the FIRST catalog to have peak flux densities above 10 mJy at 5'' resolution and deconvolved major diameters of less than 3'' at 1.4 GHz. Fifty-five of these faint radio sources were identified with accretion-powered radio galaxies and quasars brighter than 25.5 mag in the optical I band. On VLA scales at 1.4 GHz, a measure of the compactness of the faint sources (the ratio of the peak flux density from FIRST to the integrated flux density from the NVSS catalog) spans the full range of possibilities arising from source-resolution effects. Thirty of the faint radio sources, or 39{sub -7}{sup +9}%, were detected with the VLBA at 5.0 GHz with peak flux densities above 6 {sigma} {approx} 2 mJy at 2 mas resolution. The VLBA detections occur through the full range of compactness ratios. The stronger VLBA detections can themselves serve as phase-reference calibrators, boding well for opening up much of the radio sky to VLBA imaging. For the adopted cosmology, the VLBA resolution corresponds to 17 pc or finer. Most VLBA detections are unresolved or slightly resolved but one is diffuse and five show either double or core-jet structures; the properties of these latter six are discussed in detail. Eight VLBA detections are unidentified and fainter than 25.5 mag in the optical I band; their properties are highlighted because they likely mark optically-obscured active nuclei at high redshift.

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30 pages

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  • Report No.: SLAC-PUB-11282
  • Grant Number: AC02-76SF00515
  • DOI: 10.2172/890431 | External Link
  • Office of Scientific & Technical Information Report Number: 890431
  • Archival Resource Key: ark:/67531/metadc883757

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Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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Creation Date

  • June 13, 2005

Added to The UNT Digital Library

  • Sept. 21, 2016, 2:29 a.m.

Description Last Updated

  • Dec. 5, 2016, 3:41 p.m.

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Wrobel, J.M.; /NRAO, Socorro; Taylor, Greg B.; /NRAO, Socorro /KIPAC, Menlo Park; Rector, T.A.; /NRAO, Socorro /Alaska U. et al. Faint Radio Sources in the NOAO Bootes Field. VLBA Imaging And Optical Identifications, report, June 13, 2005; [Menlo Park, California]. (digital.library.unt.edu/ark:/67531/metadc883757/: accessed December 14, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.