Optical Spectroscopic Observations of Gamma-ray Blazar Candidates. V. TNG, KPNO, and OAN Observations of Blazar Candidates of Uncertain Type in the Northern Hemisphere

Abstract

The extragalactic $\gamma$-ray sky is dominated by emission from blazars, a peculiar class of active galactic nuclei (AGNs). Many of the $\gamma$-ray sources included in Fermi -Large Area Telescope Third Source catalog (3FGL) are classified as a blazar candidate of uncertain type (BCU) because there is no optical spectra available in the literature to confirm their nature. In 2013 we started a spectroscopic campaign to look for the optical counterparts of the BCUs and of the Unidentified $\gamma$-ray Sources. The main goal of our investigation is to confirm the blazar nature of these sources having peculiar properties as compact radio emission and/or selected on the basis of their infrared (IR) colors. Whenever possible we also determine their redshifts. Here we present the results of the observations carried out in the Northern hemisphere in 2013 and 2014 at Telescopio Nazionale Galilleo (TNG), Kitt Peak National Observatory (KPNO) and Observatorio Astronómico Nacional (OAN) in San Pedro Mártir. In this paper we describe the optical spectra of 25 sources. We confirmed that all the 15 BCUs observed in our campaign and included in our sample are blazars and we estimated the redshift for 3 of them. In addition, we present the spectra for 3 sources classified as BL Lacs in the literature but with no optical spectra available to date. We found that one of them is a quasar (QSO) at a redshift $z$ = 0.208 and the other 2 are BL Lacs. Moreover, we also present 7 new spectra for known blazars listed in the Roma-BZCAT having an uncertain redshift or being classified as BL Lac candidates. We found that one of them, 5BZB J0724+2621 is a `changing look' blazar. According to the spectrum available in the literature it was classified as a BL Lac but in our observation we clearly detected a broad emission line that lead to classify this source as a QSO at $z$=1.17.

21 pages, 26 figures, 3 tables, pre-proof version, published on the Astronomical Journal. arXiv admin note: text overlap with arXiv:1503.04202

References in corpus (21)

• Probing the Inner Jet of the Quasar PKS 1510-089 with Multi-waveband Monitoring during Strong Gamma-ray Activity
• The VLA Low-frequency Sky Survey
• Roma-BZCAT: A multifrequency catalogue of Blazars
• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. V. Multi-epoch VLBA Images
• The first XMM-Newton slew survey catalogue: XMMSL1
• MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. VIII. Faraday rotation in parsec-scale AGN jets
• The Origin of the Extragalactic Gamma-Ray Background and Implications for Dark-Matter Annihilation
• MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. XI. Spectral distributions
• The WISE Blazar-Like Radio-Loud Sources: An All-Sky Catalog Of Candidate Gamma-Ray Blazars
• Optical spectroscopic observations of gamma-ray blazars candidates I: preliminary results
• 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 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
• New Associations of Gamma-Ray Sources from the Fermi Second Source Catalog
• Optical spectroscopic observations of gamma-ray blazar candidates III. The 2013/2014 campaign in the Southern Hemisphere
• Gamma-Ray Active Galactic Nucleus Type through Machine-Learning Algorithms
• 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
• Characteristics of EGRET Blazars in the VLBA Imaging and Polarimetry Survey (VIPS)
• The low-frequency radio catalog of flat spectrum sources
• The changing look of PKS 2149-306

Cited by in corpus (36)

• The Central Engines of Fermi Blazars
• On the redshift of TeV BL Lac objects
• Two new catalogs of blazar candidates in the WISE infrared sky
• Optical spectroscopic observations of $\gamma$-ray blazar candidates VI. Further observations from TNG, WHT, OAN, SOAR and Magellan telescopes
• Blazar Flaring Patterns (B-FlaP): Classifying Blazar Candidates of Uncertain type in the third Fermi-LAT catalog by Artificial Neural Networks
• The Gamma-ray Blazar Quest: new optical spectra, state of art and future perspectives
• Optical spectroscopic survey of a sample of Unidentified Fermi objects
• 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
• Optical archival spectra of blazar candidates of uncertain type in the 3${}^{rd}$ Fermi Large Area Telescope Catalog
• Optical spectroscopy of BL Lac objects: TeV candidates
• Optical spectroscopic observations of gamma-ray blazar candidates VIII: the 2016-2017 follow up campaign carried out at SPM, NOT, KPNO and SOAR telescopes
• Radio Weak BL Lac objects in the Fermi era
• An optical overview of blazars with LAMOST I: Hunting changing-look blazars and new redshift estimates
• The Changing Look Blazar B2 1420+32
• Optical spectroscopy of Blazars for the Cherenkov Telescope Array
• Classification of New X-ray Counterparts for Fermi Unassociated Gamma Ray Sources Using the Swift X-Ray Telescope
• 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
• Optical spectroscopic observations of low-energy counterparts of Fermi-LAT gamma-ray sources
• ZBLLAC -- A spectroscopic database of BL Lacertae objects
• 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
• Optical Spectroscopy of Blazars for the Cherenkov Telescope Array -- II
• The Physical Properties of Changing-look Blazars
• The $\gamma$-ray sky seen at X-ray energies II: the Swift hunt of Fermi BL Lac objects among unidentified gamma-ray sources
• 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
• The Fermi-LAT view of the changing-look blazar OQ 334
• A New Multi-Wavelength Census of Blazars
• Powerful Radio Sources in the Southern Sky. I. Optical Identifications
• Identifying the 3FHL Catalog. VI. Swift Observations of 3FHL Unassociated Objects with Source Classification via Machine Learning
• 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 empirical "high-confidence" candidate zone for $Fermi$ BL Lacertae objects