Identifying the 3FHL catalog: I. Archival Swift Observations and Source Classification

Abstract

We present the results of an identification campaign of unassociated sources from the Fermi Large Area Telescope 3FHL catalog. Out of 200 unidentified sources, we selected 110 sources for which archival Swift-XRT observations were available, 52 of which were found to have exactly one X-ray counterpart within the 3FHL 95\% positional uncertainty. In this work, we report the X-ray, optical, IR, and radio properties of these 52 sources using positional associations with objects in various catalogs. The Wide-field Infrared Survey Explorer color-color plot for sources suggests that most of these belong to the blazar class family. The redshift measurements for these objects range from z=0.277 to z=2.1. Additionally, under the assumption that the majority of these sources are blazars, three machine-learning algorithms are employed to classify the sample into flat spectrum radio quasars or BL Lacertae objects. These suggest that the majority of the previously unassociated sources are BL Lac objects, in agreement with the fact the BL Lac objects represent by far the most numerous population detected above 10 GeV in 3FHL.

arXiv commentaccepted in ApJ

References in corpus (29)

• SMOTE: Synthetic Minority Over-sampling Technique
• The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III
• The 2dF Galaxy Redshift Survey: Spectra and redshifts
• The SIMBAD astronomical database
• Methods and results of an automatic analysis of a complete sample of Swift-XRT observations of GRBs
• The 6dF Galaxy Survey: Final Redshift Release (DR3) and Southern Large-Scale Structures
• The Spectral Energy Distribution of Fermi bright blazars
• SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. II. The Source Catalogue
• The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• 3FHL: The Third Catalog of Hard Fermi-LAT Sources
• The 5th edition of the Roma-BZCAT. A short presentation
• 2FHL: The Second Catalog of Hard Fermi-LAT Sources
• The First Fermi-LAT Catalog of Sources Above 10 GeV
• The Origin of the Extragalactic Gamma-Ray Background and Implications for Dark-Matter Annihilation
• The Half Million Quasars (HMQ) Catalogue
• 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
• Classification and Ranking of Fermi LAT Gamma-ray Sources from the 3FGL Catalog using Machine Learning Techniques
• Fermi's Sibyl: Mining the gamma-ray sky for dark matter subhaloes
• 3FGL Demographics Outside the Galactic Plane using Supervised Machine Learning: Pulsar and Dark Matter Subhalo Interpretations
• Spectral analysis of Fermi-LAT blazars above 50 GeV
• 3FGLzoo. Classifying 3FGL Unassociated Fermi-LAT Gamma-ray Sources by Artificial Neural Networks
• A new method to unveil blazars among multi-wavelength counterparts of Unassociated Fermi gamma-ray Sources
• Identifying the 3FHL catalog: I. Results of the KOSMOS optical spectroscopy campaign

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• The 3HSP catalogue of Extreme & High Synchrotron Peaked Blazars
• Spectral and spatial analysis of the dark matter subhalo candidates among Fermi Large Area Telescope unidentified sources
• Optical spectroscopy of Blazars for the Cherenkov Telescope Array
• Identifying the 3FHL catalog: CTIO results
• Using Neural Networks to Differentiate Newly Discovered BL Lacs and FSRQs among the 4FGL Unassociated Sources Employing Gamma-ray, X-ray, UV/Optical and IR Data
• Optical Spectroscopy of Blazars for the Cherenkov Telescope Array -- II
• The $\gamma$-ray sky seen at X-ray energies II: the Swift hunt of Fermi BL Lac objects among unidentified gamma-ray sources
• Identifying the 3FHL catalog: V. Results of the CTIO-COSMOS optical spectroscopy campaign 2019
• Searches for Pulsar-like Candidates from Unidentified Objects in the Third Catalog of Hard Fermi-LAT (3FHL) sources with Machine Learning Techniques
• Identifying the 3FHL Catalog. VI. Swift Observations of 3FHL Unassociated Objects with Source Classification via Machine Learning
• Identifying the 3FHL Catalog. IV. Swift Observations of Unassociated Fermi-LAT 3FHL Sources
• Identifying the 3FHL catalog: VI. Results of the 2019 Gemini optical spectroscopy campaign
• An empirical "high-confidence" candidate zone for $Fermi$ BL Lacertae objects