Optical spectroscopic observations of gamma-ray blazar candidates. VII. Follow-up campaign in the southern hemisphere

Peña-Herazo, H. A.; Marchesini, E. J.; Crespo, Nuria Álvarez; Ricci, F.; Massaro, F.; Chavushyan, V.; Landoni, M.; Strader, Jay; Chomiuk, Laura; Cheung, C. C.; Masetti, N.; Jiménez‐Bailón, E.; D’Abrusco, R.; Paggi, A.; Milisavljevic, Dan; Franca, F. La; Smith, H. A.; Tosti, G.

doi:10.1007/s10509-017-3208-7

Cited by 49 publications

(53 citation statements)

References 66 publications

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“…Combining our results with the results of Marchesi et al (2018), our optical spectroscopic campaign reports a redshift measurement for ≈ 23.5% of the observed BLL sources using 4 m telescopes. This measurement is in line with the expected consistency of 10 − 35%, obtained for redshift determination of pure BLL using using 4 m telescopes Ricci et al 2015;Alvarez Crespo et al 2016a;Peña-Herazo et al 2017). Moreover, our work combined with Marchesi et al (2018) also classifies, as either BLL or FSRQs, 51 blazars of previously uncertain classification.…”

Section: Resultssupporting

confidence: 90%

Identifying the 3FHL Catalog. III. Results of the CTIO-COSMOS Optical Spectroscopy Campaign

Desai

Marchesi

Rajagopal

et al. 2019

ApJS

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Active galactic Nuclei (AGNs) with their relativistic jets pointed towards the observer, form a subclass of luminous gamma-ray sources commonly known as blazars. The study of blazars is essential to improve our understanding on the AGNs emission mechanisms and evolution, as well as to map the extragalactic background light. To do so, however, one needs to correctly classify and measure a redshift for a large sample of these sources. The Third Fermi-LAT Catalog of High-Energy Sources (3FHL) contains ≈ 1160 blazars reported at energies greater than 10 GeV. However ∼25% of these sources are unclassified and ∼50% lack of redshift information. To increase the spectral completeness of the 3FHL catalog, we are working on an optical spectroscopic follow up campaign using 4-m and 8-m telescopes. In this paper, we present the results of the second part of this campaign, where we observed 23 blazars using the 4 m telescope at CTIO in Chile. We report all the 23 sources to be classified as BL Lacs, a confirmed redshift measurement for 3 sources, a redshift lower limit for 2 sources and a tentative redshift measurement for 3 sources.

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Section: Resultssupporting

confidence: 90%

Identifying the 3FHL Catalog. III. Results of the CTIO-COSMOS Optical Spectroscopy Campaign

Desai

Marchesi

Rajagopal

et al. 2019

ApJS

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“…Over the years, these observations have allowed additions to the lists of potential counterparts, which were then used with the methods previously described. In addition, to assess the real nature and classify all newly associated sources, it has been crucial to perform additional spectroscopic optical observations, which, for extragalactic objects, were also able to provide estimates of their cosmological distances (see, e.g., Shaw et al 2013aShaw et al , 2013bPaggi et al 2014;Landoni et al 2015aLandoni et al , 2015bMassaro et al 2015aMassaro et al , 2015bRicci et al 2015;Álvarez Crespo et al 2016aÁlvarez Crespo et al , 2016cChiaro et al 2016;Paiano et al 2017aPaiano et al , 2017cPaiano et al , 2017dPeña-Herazo et al 2017;Landoni et al 2018;Marchesi et al 2018;Marchesini et al 2019). These campaigns are continuously updated including searches in the optical databases of the major surveys (see, e.g., Cowperthwaite et al 2013;Massaro et al 2014Maselli et al 2015;Álvarez Crespo et al 2016b;de Menezes et al 2019).…”

Section: Automated Source Associationsmentioning

confidence: 99%

Fermi Large Area Telescope Fourth Source Catalog

Abdollahi

Acero

Ackermann

et al. 2020

ApJS

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We present the fourth Fermi Large Area Telescope catalog (4FGL) of γ-ray sources. Based on the first eight years of science data from the Fermi Gamma-ray Space Telescope mission in the energy range from 50MeV to 1TeV, it is the deepest yet in this energy range. Relative to the 3FGL catalog, the 4FGL catalog has twice as much exposure as well as a number of analysis improvements, including an updated model for the Galactic diffuse γ-ray emission, and two sets of light curves (one-year and two-month intervals). The 4FGL catalog includes 5064 sources above 4σ significance, for which we provide localization and spectral properties. Seventy-five sources are modeled explicitly as spatially extended, and overall, 358 sources are considered as identified based on angular extent, periodicity, or correlated variability observed at other wavelengths. For 1336 sources, we have not found plausible counterparts at other wavelengths. More than 3130 of the identified or associated sources are active galaxies of the blazar class, and 239 are pulsars.

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“…All our data were acquired, reduced and analyzed following the same method adopted in our previous analyses of this spectroscopic campaign. Here we reported only the basic details regarding the data collection and a brief overview of our standard procedure used for the extraction of the optical spectra, more information can be found in our previous works (see e.g., Ricci et al 2015;Álvarez Crespo et al 2016b;Álvarez Crespo et al 2016c;Peña-Herazo et al 2017, for additional details).…”

Section: Data Reductionmentioning

confidence: 99%

Optical spectroscopic observations of gamma-ray blazar candidates VIII: the 2016–2017 follow up campaign carried out at SPM, NOT, KPNO and SOAR telescopes

Marchesini

Peña-Herazo

Crespo

et al. 2019

Astrophys Space Sci

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The third Fermi source catalog lists 3033 γray sources above 4σ significance. More than 30% are classified as either unidentified/unassociated Gammaray sources (UGSs), with about 20% classified as Blazar candidates of uncertain types (BCUs). To confirm the blazar-like nature of candidate counterparts of UGSs and BCUs, we started in 2012 an optical spectroscopic follow up campaign. We report here the spectra of 36 targets with observations from the Observatorio Astronómico Nacional San Pedro Mártir, the Southern Astrophysical Research Observatory, the Kitt Peak National Observatory and the Northern Optical Telescope, between 2016 and 2017. We confirm the BL Lac nature of 23 sources, and the flat spectrum radio quasar nature of other 7 ones. We also provide redshift estimates for 19 out of these 30 confirmations, with only one being a lower limit due to spectral features ascribable to intervening systems along the line of sight. As in previous analyses, the largest fraction of now-classified BCUs belong to the class of BL Lac objects, that appear to be the most elusive class of active galactic nuclei. One of the BL Lacs identified in this work, associated with 3FGL J2213.6-4755, lies at a redshift of z >1.529, making it one of the few distant gamma-ray BL Lac objects.

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Optical spectroscopic observations of gamma-ray blazar candidates. VII. Follow-up campaign in the southern hemisphere

Cited by 49 publications

References 66 publications

Identifying the 3FHL Catalog. III. Results of the CTIO-COSMOS Optical Spectroscopy Campaign

Identifying the 3FHL Catalog. III. Results of the CTIO-COSMOS Optical Spectroscopy Campaign

Fermi Large Area Telescope Fourth Source 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

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