Radio Weak BL Lac objects in the Fermi era

Abstract

The existence of "radio weak BL Lac objects" (RWBLs) has been an open question, still unsolved, since the discovery that quasars could be radio-quiet or radio-loud. Recently several groups identified RWBL candidates, mostly found while searching for low energy counterparts of the unidentified/unassociated gamma-ray sources listed in the Fermi catalogs. Confirming RWBLs is a challenging task since they could be confused with white dwarfs (WDs) or weak emission line quasars (WELQs) when there are not sufficient data to precisely draw their broad band spectral energy distribution and their classification is mainly based on a featureless optical spectra. Motivated by the recent discovery that Fermi BL Lacs appear to have very peculiar mid-IR emission, we show that it is possible to distinguish between WDs, WELQs and BL Lacs using the [3.4]-[4.6]-[12]$\mu$m color-color plot built using the WISE magnitudes when the optical spectrum is available. On the basis of this analysis, we identify WISE J064459.38+603131 and WISE J141046.00+740511.2 as the first two genuine RWBLs, both potentially associated with Fermi sources. Finally, to strengthen our identification of these objects as true RWBLs, we present multifrequency observations for these two candidates to show that their spectral behavior is indeed consistent with those of the BL Lac population.

arXiv comment12 pages, 9 figures, ApJ accepted for publication, pre-proof version

References in corpus (83)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Unified Schemes for Radio-Loud Active Galactic Nuclei
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• Observational Evidence of AGN Feedback
• The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III
• Interstellar Dust Grains
• Fermi Large Area Telescope Second Source Catalog
• Fermi Large Area Telescope First Source Catalog
• The Second Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• The Connection between X-ray- and Radio-Selected BL Lacertae Objects
• The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• The First Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• Roma-BZCAT: A multifrequency catalogue of Blazars
• SDSS DR7 White Dwarf Catalog
• Log-parabolic spectra and particle acceleration in the BL Lac object Mkn 421: spectral analysis of the complete BeppoSAX wide band X-ray data set
• The 5th edition of the Roma-BZCAT. A short presentation
• The Last of FIRST: The Final Catalog and Source Identifications
• The Cosmic Evolution of Fermi BL Lacertae Objects
• New white dwarf stars in the Sloan Digital Sky Survey Data Release 10
• The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars
• Spectroscopy of The Largest Ever Gamma-ray Selected BL Lac Sample
• Log-parabolic spectra and particle acceleration in blazars. III: SSC emission in the TeV band from Mkn 501
• The First Fermi-LAT Catalog of Sources Above 10 GeV
• Identification of the infrared non-thermal emission in Blazars
• High-Redshift SDSS Quasars with Weak Emission Lines
• Contribution of the Gamma-ray Loud Radio Galaxies Core Emissions to the Cosmic MeV and GeV Gamma-Ray Background Radiation
• Swift X-ray Telescope Monitoring of Fermi-LAT Gamma Ray Sources of Interest
• The RGB Sample of Intermediate BL Lacs
• An Optical View of BL Lacertae Objects
• The WIRED Survey II: Infrared Excesses in the SDSS DR7 White Dwarf Catalog
• X-ray spectral evolution of TeV BL Lac objects: eleven years of observations with BeppoSAX, XMM-Newton and SWIFT satellites
• The WISE gamma-ray strip parametrization: the nature of the gamma-ray Active Galactic Nuclei of Uncertain type
• The WISE Blazar-Like Radio-Loud Sources: An All-Sky Catalog Of Candidate Gamma-Ray Blazars
• Diffuse $\gamma$-ray emission from misaligned active galactic nuclei
• Chandra Observations of the Highest Redshift Quasars from the Sloan Digital Sky Survey
• Infrared Colors of the gamma-ray detected blazars
• Optically identified BL Lacertae objects from the Sloan Digital Sky Survey
• Unveiling the nature of the unidentified gamma-ray sources I: a new method for the association of gamma-ray blazars
• X-ray and Multiwavelength Insights into the Nature of Weak Emission-Line Quasars at Low Redshift
• Polarization microvariability of BL Lac objects
• A Large Sample of BL Lacs from SDSS and FIRST
• Optical spectroscopic observations of gamma-ray blazars candidates I: preliminary results
• Optical spectroscopic observations of $\gamma$-ray blazar candidates VI. Further observations from TNG, WHT, OAN, SOAR and Magellan telescopes
• Detection of Rest-frame Optical Lines from X-shooter Spectroscopy of Weak Emission Line Quasars
• 1WHSP: an IR-based sample of $\sim$1,000 VHE $\gamma$-ray blazar candidates
• Unveiling the nature of the unidentified gamma-ray sources II: radio, infrared and optical counterparts of the gamma-ray blazar candidates
• Optical spectroscopic observations of blazars and gamma-ray blazar candidates in the Sloan Digital Sky Survey Data Release Nine
• Unveiling the nature of the unidentified gamma-ray sources III: gamma-ray blazar-like counterparts at low radio frequencies
• X-ray Insights into the Nature of Weak Emission-Line Quasars at High Redshift
• The WIRED Survey. IV. New Dust Disks from the McCook & Sion White Dwarf Catalog
• Unveiling the nature of the unidentified gamma-ray sources IV: the $\text{Swift}$ catalog of potential X-ray counterparts
• Optical spectroscopic observations of gamma-ray blazar candidates II. The 2013 KPNO campaign in the Northern Hemisphere
• Optical Spectroscopic Observations of Gamma-ray Blazar Candidates. V. TNG, KPNO, and OAN Observations of Blazar Candidates of Uncertain Type in the Northern Hemisphere
• Unidentifed gamma-ray sources: hunting gamma-ray blazars
• Optical spectroscopic observations of gamma-ray blazar candidates III. The 2013/2014 campaign in the Southern Hemisphere
• Multiwavelength Observations of Radio-quiet Quasars with Weak Emission Lines
• BL Lac candidates for TeV observations
• SSC radiation in BL Lac sources, the end of the tether
• Optical spectroscopic observations of gamma-ray blazar candidates IV. Results of the 2014 follow-up campaign
• Refining the associations of the Fermi Large Area Telescope Source Catalogs
• The Infrared-Gamma-Ray Connection: A WISE View of the Extragalactic Gamma-Ray Sky
• The colours of BL Lac objects: a new approach to their classification
• High-energy sources at low radio frequency: the Murchison Widefield Array view of Fermi blazars
• A large sample of Kohonen-selected SDSS quasars with weak emission lines: selection effects and statistical properties
• The low-frequency radio catalog of flat spectrum sources
• Blazars spectral properties at 74 MHz
• Optical archival spectra of blazar candidates of uncertain type in the 3${}^{rd}$ Fermi Large Area Telescope Catalog
• Highly Polarized Optically-Selected BL Lacertae Objects
• Unveiling the nature of the unidentified gamma-ray sources VI: gamma-ray blazar candidates in the WISH survey and their radio properties
• The 2dF BL Lac Survey
• 2QZJ215454.3-305654: a radio-quiet BL Lac object or lineless QSO?
• Swift observations of IBL and LBL objects
• Fueling lobes of radio galaxies: statistical particle acceleration and the extragalactic gamma-ray background
• The Ultraviolet-to-Mid-Infrared Spectral Energy Distribution of Weak Emission Line Quasars
• Looking for blazars in a sample of unidentified high-energy emitting Fermi sources
• Swift/XRT counterparts to unassociated Fermi high-energy LAT sources
• Searching for new gamma-ray blazar candidates in the 3rd Palermo BAT Hard X-ray Catalog with WISE
• Swift observations of unidentified radio sources in the revised Third Cambridge Catalogue
• AGN feedback in clusters: shock and sound heating
• 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
• Compact sources in the Bologna Complete Sample: high resolution VLA observations and optical data
• The 26 year-long X-ray light curve and the X-ray spectrum of the BL Lac Object 1E 1207.9+3945 in its brightest state

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• The Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
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• Dark matter in the Reticulum II dSph: a radio search
• Optical Spectroscopic Observations of Gamma-Ray Blazar Candidates. VII. Follow-up Campaign in the Southern Hemisphere
• Optical spectroscopic observations of gamma-ray blazar candidates VIII: the 2016-2017 follow up campaign carried out at SPM, NOT, KPNO and SOAR telescopes
• An optical overview of blazars with LAMOST I: Hunting changing-look blazars and new redshift estimates
• Optical spectroscopic observations of gamma-ray blazar candidates. IX. Optical archival spectra and further observations from SOAR and OAGH
• The sequence of Compton dominance in blazars based on data from WISE and Fermi/LAT
• Optical spectroscopic observations of gamma-ray blazar candidates. X. Results from the 2018--2019 SOAR and OAN-SPM observations of blazar candidates of uncertain type
• Optical spectroscopic observations of low-energy counterparts of Fermi-LAT gamma-ray sources
• Multi-wavelength variability of CGRaBS J0733+0456: identifying a distant $\gamma$-ray blazar at z = 3.01
• The strange case of the transient HBL blazar 4FGL J1544.3-0649
• FERMI transient J1544-0649: a flaring radio-weak BL Lac
• Shedding New Light on Weak Emission-Line Quasars in the C${}_{\mathrm{IV}}$-H$\beta$ Parameter Space
• Faint $\gamma$-ray sources at low-redshift: the radio galaxy IC 1531
• Optical spectroscopic characterization of Fermi blazar candidates of uncertain type with TNG and DOT: First Results
• The loud and the quiet: searching for radio counterparts of two radio-weak BL Lac candidates with VLBI
• Superluminal Motion and Jet Parameters in the Gamma-ray-Emitting Narrow-Line Seyfert 1 Galaxy TXS 1206+549
• An XMM-Newton look at the strongly variable radio-weak BL Lac Fermi J1544-0639
• Disentangling the nature of the prototype radio weak BL Lac: Contemporaneous multifrequency observations of WISE J141046.00 + 740511.2
• New blazar candidates from the 9Y-MST catalogue detected at energies higher than 10 GeV
• Multiwavelength study of potential blazar candidates among Fermi-LAT unidentified gamma-ray sources