The 2dF BL Lac Survey II

Abstract

We report on our further analysis of the expanded and revised sample of potential BL Lac objects (the 2BL) optically identified from two catalogues of blue-selected (UV excess) point sources, the 2dF and 6dF QSO Redshift Surveys (2QZ and 6QZ). The 2BL comprises 52 objects with no apparent proper motion, over the magnitude range 16.0 < bj< 20.0. Follow-up high signal-to-noise spectra of 36 2BL objects and NIR imaging of 18 objects, together with data for 19 2BL objects found in the Sloan Digital Sky survey (SDSS), show 17 objects to be stellar, while a further 16 objects have evidence of weak, broad emission features, although for at least one of these the continuum level has clearly varied. Classification of three objects remains uncertain,with NIR results indicating a marked reduction in flux as compared to SDSS optical magnitudes. Seven objects have neither high signal-to-noise spectra nor NIR imaging. Deep radio observations of 26 2BL objects at the VLA resulted in only three further radio-detections, however none of the three is classed as a featureless continuum object. Seven 2BL objects with a radio detection are confirmed as candidate BL Lac objects while one extragalactic (z=0.494) continuum object is undetected at radio frequencies. One further radio-undetected object is also a potential BL Lac candidate. However it would appear that there is no significant population of radio-quiet BL Lac objects.

accepted for publication in MNRAS

References in corpus (18)

• Unified Schemes for Radio-Loud Active Galactic Nuclei
• The 2dF Galaxy Redshift Survey: Spectra and redshifts
• The 2dF QSO Redshift Survey - XII. The spectroscopic catalogue and luminosity function
• SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. I. Science goals, survey design and instrumentation
• Photometric and Spectroscopic Analysis of Cool White Dwarfs with Trigonometric Parallax Measurements
• JHK Standard Stars for Large Telescopes: the UKIRT Fundamental and Extended Lists
• Northern JHK Standard Stars for Array Detectors
• The 2dF QSO Redshift Survey - V. The 10k catalogue
• The SuperCOSMOS Sky Survey. Paper III: Astrometry
• The Lack of BLR in Low Accretion Rate AGN as Evidence of their Origin in the Accretion Disk
• The Properties of the X-Ray-Selected EMSS Sample of BL Lac Objects
• Quasars in the 2MASS Second Incremental Data Release
• Optically identified BL Lacertae objects from the Sloan Digital Sky Survey
• Discovery of Radio-loud Broad Absorption Line Quasars Using Ultraviolet Excess and Deep Radio Selection
• A Very Low-Luminosity, Very Cool, DC White Dwarf
• The 2dF BL Lac Survey
• 2QZJ215454.3-305654: a radio-quiet BL Lac object or lineless QSO?
• Optical follow-up of BL Lac candidates in the 2BL sample

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• The Central Engines of Fermi Blazars
• A Large Sample of BL Lacs from SDSS and FIRST
• The Relativistic Jet Dichotomy and the End of the Blazar Sequence
• Polarimetry of optically selected BL Lac candidates from the SDSS
• Incidence of MgII absorbers towards Blazars and the GRB/QSO puzzle
• Highly Variable Objects in the Palomar-QUEST Survey: A Blazar Search using Optical Variability
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