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

Abstract

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. Formore » 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.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
890431
Report Number(s):
SLAC-PUB-11282
astro-ph/0506193; TRN: US200620%%461
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COSMOLOGY; FLUX DENSITY; NUCLEI; OPENINGS; QUASARS; RADIO GALAXIES; RESOLUTION; SKY; Astrophysics,ASTRO

Citation Formats

Wrobel, J M, /NRAO, Socorro, Taylor, Greg B, /NRAO, Socorro /KIPAC, Menlo Park, Rector, T A, /NRAO, Socorro /Alaska U., Myers, S T, /NRAO, Socorro, Fassnacht, C D, and /UC,Davis. Faint Radio Sources in the NOAO Bootes Field. VLBA Imaging And Optical Identifications. United States: N. p., 2005. Web. doi:10.2172/890431.
Wrobel, J M, /NRAO, Socorro, Taylor, Greg B, /NRAO, Socorro /KIPAC, Menlo Park, Rector, T A, /NRAO, Socorro /Alaska U., Myers, S T, /NRAO, Socorro, Fassnacht, C D, & /UC,Davis. Faint Radio Sources in the NOAO Bootes Field. VLBA Imaging And Optical Identifications. United States. https://doi.org/10.2172/890431
Wrobel, J M, /NRAO, Socorro, Taylor, Greg B, /NRAO, Socorro /KIPAC, Menlo Park, Rector, T A, /NRAO, Socorro /Alaska U., Myers, S T, /NRAO, Socorro, Fassnacht, C D, and /UC,Davis. 2005. "Faint Radio Sources in the NOAO Bootes Field. VLBA Imaging And Optical Identifications". United States. https://doi.org/10.2172/890431. https://www.osti.gov/servlets/purl/890431.
@article{osti_890431,
title = {Faint Radio Sources in the NOAO Bootes Field. VLBA Imaging And Optical Identifications},
author = {Wrobel, J M and /NRAO, Socorro and Taylor, Greg B and /NRAO, Socorro /KIPAC, Menlo Park and Rector, T A and /NRAO, Socorro /Alaska U. and Myers, S T and /NRAO, Socorro and Fassnacht, C D and /UC,Davis},
abstractNote = {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.},
doi = {10.2172/890431},
url = {https://www.osti.gov/biblio/890431}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2005},
month = {6}
}