J/ApJS/248/23 4FGL sources with IR/Rad associations (de Menezes+, 2020)
On the physical association of Fermi-LAT blazars with their low-energy
counterparts.
de Menezes R., D'Abrusco R., Massaro F., Gasparrini D., Nemmen R.
<Astrophys. J. Suppl. Ser., 248, 23 (2020)>
=2020ApJS..248...23D 2020ApJS..248...23D
ADC_Keywords: Active gal. nuclei; Gamma rays; Infrared sources; Radio sources;
Cross identifications
Keywords: Gamma-ray astronomy ; Active galactic nuclei ; Astronomical methods
Abstract:
Associating γ-ray sources to their low-energy counterparts is
one of the major challenges of modern γ-ray astronomy. In the
context of the Fourth Fermi Large Area Telescope Source Catalog
(4FGL), the associations rely mainly on parameters such as apparent
magnitude, integrated flux, and angular separation between the
γ-ray source and its low-energy candidate counterpart. In this
work, we propose a new use of the likelihood ratio (LR) and a
complementary supervised learning technique to associate γ-ray
blazars in 4FGL, based only on spectral parameters such as the
γ-ray photon index, mid-infrared colors, and radio-loudness. In
the LR approach, we crossmatch the Wide-field Infrared Survey Explorer
Blazar-Like Radio-Loud Sources catalog with 4FGL and compare the
resulting candidate counterparts with the sources listed in the
γ-ray blazar locus to compute an association probability (AP)
for 1138 counterparts. In the supervised learning approach, we train a
random forest algorithm with 869 high-confidence blazar associations
and 711 fake associations and then compute an AP for 1311 candidate
counterparts. A list with all 4FGL blazar candidates of uncertain type
associated by our method is provided to guide future optical
spectroscopic follow-up observations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 59 283 Blazar candidates of an uncertain type (BCUs)
associated by the likelihood ratio (LR) method
based only on spectral parameters
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See also:
VII/169 : Optical Identifications of IRAS Point Sources (Wang+ 1986,87,91)
VII/274 : The Roma BZCAT - 5th edition (Massaro+, 2015)
II/328 : AllWISE Data Release (Cutri+ 2013)
J/PASP/113/10 : Sub-mJy radio sources complete sample (Masci+, 2001)
J/ApJS/188/405 : Fermi-LAT first source catalog (1FGL) (Abdo+, 2010)
J/ApJ/743/171 : The 2LAC catalog (Ackermann+, 2011)
J/ApJ/748/68 : WISE IR colors of gamma-ray blazars (D'Abrusco+, 2012)
J/MNRAS/424/L64 : AGN/pulsar distinction for 2FGL sources (Mirabal+, 2012)
J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)
J/ApJS/206/12 : Blazars with γ-ray counterparts. I. (D'Abrusco+, 2013)
J/MNRAS/428/220 : Gamma-ray AGN type determination (Hassan+, 2013)
J/ApJS/209/10 : UGSs. V. kernel approach (Massaro+, 2013)
J/ApJS/215/14 : WISE γ-ray blazar radio sources (D'Abrusco+, 2014)
J/ApJ/782/41 : 231 AGN candidates from the 2FGL catalog (Doert+, 2014)
J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)
J/ApJS/217/2 : Refined associations of Fermi/LAT sources (Massaro+, 2015)
J/MNRAS/462/3180 : 3FGL Blazar of Unknown Type classification (Chiaro+, 2016)
J/ApJ/820/8 : 3FGL sources statistical classif. (Saz Parkinson+, 2016)
J/A+A/602/A86 : Blazar cand. among Fermi/LAT 3FGL cat. (Lefaucheur+, 2017)
J/MNRAS/470/1291 : Classifying 3FGL with ANN (Salvetti+, 2017)
J/ApJS/242/4 : Two new catalogs of blazar candidates (D'Abrusco+, 2019)
J/ApJS/247/33 : The Fermi LAT fourth source cat. (4FGL) (Abdollahi+, 2020)
J/MNRAS/493/1926 : 4FGL blazar classification neural network (Kovacevic+, 2020)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [4FGL]
6- 17 A12 --- 4FGL The 4FGL identifier (JHHMM.m+DDMM)
19- 37 A19 --- WISEA The WISE counterpart identifier
(JHHMMSS.ss+DDMMSS.s; WIBRaLS sources
from D'Abrusco+, 2019, J/ApJS/242/4)
38- 39 A2 --- f_WISEA Flag on WISEA (1)
41- 44 F4.2 --- LR [0.85/1] Association probability
by LR method from this work (2)
46- 49 F4.2 --- RF [0.08/1] Association probability
by random forest method from this work
(see Section 5)
51- 54 F4.2 --- Bay [0/1]? Association probability by Bayesian
method used in 4FGL
56- 59 F4.2 --- LR4FGL [0/1] Association probability by LR method
used in 4FGL
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Note (1): Flag as follows:
* = confirmed blazar. Optical spectra available in
de Menezes+ 2020Ap&SS.365...12D 2020Ap&SS.365...12D (13 occurrences).
** = confirmed blazar, Optical spectra available in
Pena-Herazo et al. (2020, in prep -- 4 occurrences).
Note (2): The likelihood ratio (LR) method we adopt to estimate the association
probability is a modification of the LR method described in Sutherland
& Saunders (1992MNRAS.259..413S 1992MNRAS.259..413S) and Ackermann+ (2011, J/ApJ/743/171).
See Section 4.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 20-Jul-2020