Optical spectroscopic observations of $\gamma$-ray blazar candidates VI. Further observations from TNG, WHT, OAN, SOAR and Magellan telescopes

Abstract

Blazars, one of the most extreme class of active galaxies, constitute so far the largest known population of $\gamma$-ray sources and their number is continuously growing in the Fermi catalogs. However in the latest release of the Fermi catalog there is still a large fraction of sources that are classified as blazar candidate of uncertain type (BCUs) for which optical spectroscopic observations are necessary to confirm their nature and their associations. In addition about 1/3 of the $\gamma$-ray point sources listed in the Third Fermi-LAT Source Catalog (3FGL) are still unassociated and lacking an assigned lower energy counterpart. Since 2012 we have been carrying out an optical spectroscopic campaign to observe blazar candidates to confirm their nature. In this paper, the sixth of the series, we present optical spectroscopic observations for 30 $\gamma$-ray blazar candidates from different observing programs we carried out with the TNG, WHT, OAN, SOAR and Magellan telescopes. We found that 21 out of 30 sources investigated are BL Lac objects while the remaining targets are classified as flat spectrum radio quasars showing the typical broad emission lines of normal quasi stellar objects. We conclude that our selection of $\gamma$-ray blazars candidates based on their multifrequency properties continues to be a successful way to discover potential low-energy counterparts of the FermiUnidentified Gamma-ray Sources (UGSs) and to confirm the nature of BCUs.

References in corpus (49)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission
• The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
• Fermi Large Area Telescope Second Source Catalog
• Fermi Large Area Telescope First Source Catalog
• The 6dF Galaxy Survey: Final Redshift Release (DR3) and Southern Large-Scale Structures
• The Chandra Source Catalog
• The 6dF Galaxy Survey: Samples, Observational Techniques and the First Data Release
• The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• CRATES: An All-Sky Survey of Flat-Spectrum Radio Sources
• The VLA Low-frequency Sky Survey
• Roma-BZCAT: A multifrequency catalogue of Blazars
• The Australia Telescope 20 GHz Survey: The Source Catalogue
• The first XMM-Newton slew survey catalogue: XMMSL1
• CGRaBS: An All-Sky Survey of Gamma-Ray Blazar Candidates
• Spectroscopy of The Largest Ever Gamma-ray Selected BL Lac Sample
• The First Fermi-LAT Catalog of Sources Above 10 GeV
• 1SXPS: A deep Swift X-ray Telescope point source catalog with light curves and spectra
• Swift X-ray Telescope Monitoring of Fermi-LAT Gamma Ray Sources of Interest
• 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
• A Statistical Approach to Recognizing Source Classes for Unassociated Sources in the First Fermi-LAT Catalog
• Infrared Colors of the gamma-ray detected blazars
• Unveiling the nature of the unidentified gamma-ray sources I: a new method for the association of gamma-ray blazars
• The classification of BL Lacertae objects: the Ca H&K break
• Correlation of Fermi-LAT sources with the AT20GHz radio survey
• Optical spectroscopic observations of gamma-ray blazars candidates I: preliminary results
• High-frequency radio properties of sources in the Fermi-LAT 1-year Point Source Catalogue
• Australia Telescope Compact Array observations of Fermi unassociated sources
• 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
• Gamma-ray flaring activity from the gravitationally lensed blazar PKS 1830-211 observed by Fermi LAT
• Unveiling the nature of the unidentified gamma-ray sources III: gamma-ray blazar-like counterparts at low radio frequencies
• 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. V. TNG, KPNO, and OAN Observations of Blazar Candidates of Uncertain Type in the Northern Hemisphere
• New Associations of Gamma-Ray Sources from the Fermi Second Source Catalog
• Optical spectroscopic observations of gamma-ray blazar candidates II. The 2013 KPNO campaign 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
• Optical spectroscopic observations of gamma-ray blazar candidates IV. Results of the 2014 follow-up campaign
• Search for gamma-ray-emitting active galactic nuclei in the Fermi-LAT unassociated sample using machine learning
• Redshifts of CLASS Radio Sources
• Unveiling the nature of the unidentified gamma-ray sources V: analysis of the radio candidates with the kernel density estimation
• Refining the associations of the Fermi Large Area Telescope Source Catalogs
• BL Lacertae identifications in a ROSAT-selected sample of Fermi unidentified objects
• Blazars spectral properties at 74 MHz
• The XMM-Newton slew survey in the 2-10 keV band
• Multiband Diagnostics of Unidentified 1FGL Sources with Suzaku and Swift X-ray Observations

Cited by in corpus (45)

• Fermi Large Area Telescope Fourth Source Catalog
• The Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• 3FHL: The Third Catalog of Hard Fermi-LAT Sources
• The Central Engines of Fermi Blazars
• MOJAVE XIX: Brightness Temperatures and Intrinsic Properties of Blazar Jets
• Two new catalogs of blazar candidates in the WISE infrared sky
• The Gamma-ray Blazar Quest: new optical spectra, state of art and future perspectives
• Optical spectroscopic survey of a sample of Unidentified Fermi objects
• Research and characterisation of blazar candidates among the Fermi/LAT 3FGL catalogue using multivariate classifications
• Optical Spectroscopic Observations of Gamma-Ray Blazar Candidates. VII. Follow-up Campaign in the Southern Hemisphere
• The Infrared-Gamma-Ray Connection: A WISE View of the Extragalactic Gamma-Ray Sky
• 3FGLzoo. Classifying 3FGL Unassociated Fermi-LAT Gamma-ray Sources by Artificial Neural Networks
• Astrometric Limits on the Stochastic Gravitational Wave Background
• Optical spectroscopic survey of a sample of Unidentified Fermi objects: II
• Optical archival spectra of blazar candidates of uncertain type in the 3${}^{rd}$ Fermi Large Area Telescope Catalog
• 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
• Radio Weak BL Lac objects in the Fermi era
• Optical spectroscopy of Blazars for the Cherenkov Telescope Array
• New High-z Fermi BL Lacs with the Photometric Dropout Technique
• Classification of New X-ray Counterparts for Fermi Unassociated Gamma Ray Sources Using the Swift X-Ray Telescope
• A new method to unveil blazars among multi-wavelength counterparts of Unassociated Fermi gamma-ray Sources
• Optical spectroscopic observations of gamma-ray blazar candidates. IX. Optical archival spectra and further observations from SOAR and OAGH
• Identifying the 3FHL catalog: CTIO results
• Identifying the 3FHL catalog: I. Results of the KOSMOS optical spectroscopy campaign
• Optical spectroscopic observations of low-energy counterparts of Fermi-LAT gamma-ray sources
• Optical characterization of WISE selected blazar candidates
• New high-z BL Lacs using the photometric method with Swift and SARA
• The $\gamma$-ray sky seen at X-ray energies I. Searching for the connection between X-rays and $\gamma$-rays in Fermi BL Lac objects
• ZBLLAC -- A spectroscopic database of BL Lacertae objects
• The $\gamma$-ray sky seen at X-ray energies II: the Swift hunt of Fermi BL Lac objects among unidentified gamma-ray sources
• Optical Spectroscopy of Blazars for the Cherenkov Telescope Array -- II
• Evaluating Optical Classification for {\em Fermi} Blazar Candidates with a Statistical method using Broadband Spectral Indices
• Identifying the 3FHL catalog: V. Results of the CTIO-COSMOS optical spectroscopy campaign 2019
• On the physical association of Fermi-LAT blazars with their low-energy counterparts
• Highly Variable Active Galactic Nuclei in the SRG/eROSITA All-Sky Survey: I. Constructing Sample and Catalog of Sources Detected in Low State
• Characterising the extended morphologies of BL Lacs at 144 MHz with LOFAR
• Relativistic plasmas in AGN jets - From synchrotron radiation to $\gamma$-ray emission
• Optical spectroscopic characterization of Fermi blazar candidates of uncertain type with TNG and DOT: First Results
• Classifying blazar candidates from the 3FGL unassociated catalog into BL Lacs and FSRQs using Swift and WISE data
• Identifying the 3FHL catalog: VI. Results of the 2019 Gemini optical spectroscopy campaign
• An XMM-Newton catalogue of BL Lacs
• An empirical "high-confidence" candidate zone for $Fermi$ BL Lacertae objects
• Searching for Gamma-Ray Millisecond Pulsars: Selection of Candidates Revisited
• On the origin of mid-infrared colors in $\gamma$-ray blazars