Optically identified BL Lacertae objects from the Sloan Digital Sky Survey

Abstract

We present a sample of 386 BL Lacertae (BL Lac) candidates identified from 2860 deg^2 of the Sloan Digital Sky Survey (SDSS) spectroscopic database. The candidates are primarily selected to have quasi-featureless optical spectra and low proper motions as measured from SDSS and USNO-B positions; however, our ability to separate Galactic from extragalactic quasi-featureless objects (QFOs) on the basis of proper motion alone is limited by the lack of reliable proper motion measurements for faint objects. Fortunately, high proper motion QFOs, mostly DC white dwarfs, populate a well defined region of color space, approximately corresponding to blackbodies with temperatures in the range 7000-12000 K. QFOs with measurable redshifts or X-ray or radio counterparts (i.e., evidence of an extragalactic/AGN nature) loosely follow a track in color space that corresponds to power-law continua plus host galaxy starlight, with typical power-law slopes in the range 1<alpha_{opt}<2 (f_{nu} propto nu^{-alpha}). Based largely on this remarkably clean color separation, we subdivide the sample into 240 probable candidates and 146 additional less probable (likely stellar) candidates. The probable BL Lac candidates have multi-wavelength properties consistent with the range of previously known BL Lacs, with an apparent preponderance of objects with synchrotron peaks at relatively high energies (HBL/ XBL-type). The majority of the 154 objects with measurable redshifts have z<1, with a median of 0.45; there are also a handful of high-redshift objects extending up to z=5.03. We identify a small number of potential radio-quiet BL Lac candidates, although more sensitive radio observations are needed to confirm their radio-quiet nature.

42 pages, 11 figures (4 in color), uses aastex.cls. To appear in the June 2005 edition of AJ. Full tables are temporarily available from http://www.astro.princeton.edu/~collinge/sdss_bllac/ and will be published electronically. Summary of changes: 1) improved SDSS/USNO-B proper motion treatment; 2) improved discussion of multiwavelength properties

References in corpus (36)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Sloan Digital Sky Survey: Technical Summary
• Unified Schemes for Radio-Loud Active Galactic Nuclei
• The USNO-B Catalog
• Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Main Galaxy Sample
• The Sloan Digital Sky Survey Photometric Camera
• The u'g'r'i'z' Standard Star Network
• A Unifying View of the Spectral Energy Distributions of Blazars
• The Second Data Release of the Sloan Digital Sky Survey
• Spectroscopic Target Selection for the Sloan Digital Sky Survey: The Luminous Red Galaxy Sample
• Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Quasar Sample
• The First Data Release of the Sloan Digital Sky Survey
• Astrometric Calibration of the Sloan Digital Sky Survey
• A theoretical unifying scheme for gamma-ray bright blazars
• A photometricity and extinction monitor at the Apache Point Observatory
• The Connection between X-ray- and Radio-Selected BL Lacertae Objects
• An Efficient Algorithm for Positioning Tiles in the Sloan Digital Sky Survey
• The 2dF QSO Redshift Survey - I. The Optical QSO Luminosity Function
• Optical and Radio Properties of Extragalactic Sources Observed by the FIRST and SDSS Surveys
• The Ensemble Photometric Variability of ~25000 Quasars in the Sloan Digital Sky Survey
• SDSS Data Management and Photometric Quality Assessment
• Unusual Broad Absorption Line Quasars from the Sloan Digital Sky Survey
• A Catalog of Spectroscopically Identified White Dwarf Stars in the First Data Release of the Sloan Digital Sky Survey
• The Deep X-ray Radio Blazar Survey (DXRBS). I. Methods and First Results
• The Discovery of a High-redshift Quasar without Emission Lines from Sloan Digital Sky Survey Commissioning Data
• A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky Survey Early Data Release
• Optical and Infrared Colors of Stars Observed by 2MASS and SDSS
• The Properties of the X-Ray-Selected EMSS Sample of BL Lac Objects
• High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data VI. Sloan Digital Sky Survey Spectrograph Observations
• An Empirical Calibration of the Completeness of the SDSS Quasar Survey
• A Large, Uniform Sample of X-ray Emitting AGN: Selection Approach and an Initial Catalog from the ROSAT All-Sky and Sloan Digital Sky Surveys
• The classification of BL Lacertae objects: the Ca H&K break
• The recognition of blazars and the blazar spectral sequence
• Proper Motion Catalog From SDSS \intersect USNO-B
• The 2dF BL Lac Survey
• 2QZJ215454.3-305654: a radio-quiet BL Lac object or lineless QSO?

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• The Sloan Digital Sky Survey Quasar Catalog III. Third Data Release
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• Chandra Observations of the Highest Redshift Quasars from the Sloan Digital Sky Survey
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• Weak-Line Quasars at High Redshift: Extremely High Accretion Rates or Anemic Broad-Line Regions?
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• Application of the MST clustering to the high energy gamma-ray sky. III - New detections of gamma-ray emission from blazars
• Final stage of merging binaries of supermassive black holes: observational signatures
• Intranight Optical Variability of Radio-Quiet Weak Emission Line Quasars-II
• Intranight Optical Variability of Radio-Quiet Weak Emission Line Quasars-IV
• Optical spectroscopy of SDSS J004054.65-0915268: three possible scenarios for the classification. A z \sim 5 BL Lacertae, blue FSRQ or a weak emission line quasar
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• Properties of optically selected BL Lac candidates from the SDSS
• Optical identification of radio-loud active galactic nuclei in the ROSAT-Green-Bank sample with SDSS spectroscopy
• Rarefied Broad-Line Regions in Active Galactic Nuclei: Anomalous Responses in Reverberation Mapping and Implications for Weak Emission-Line Quasars
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