J/ApJ/943/167 FSRQs & BL Lac objects from 4FGL blazar candidates (Kaur+, 2023)
Using neural networks to differentiate newly discovered BL Lacertae objects and
FSRQs among the 4FGL unassociated sources employing gamma-ray, X-ray,
UV/Optical, and IR data.
Kaur A., Kerby S., Falcone A.D.
<Astrophys. J., 943, 167 (2023)>
=2023ApJ...943..167K 2023ApJ...943..167K
ADC_Keywords: BL Lac objects; QSOs; Active gal. nuclei; Gamma rays;
X-ray sources; Colors; Infrared; Optical; Ultraviolet
Keywords: High energy astrophysics ; Active galactic nuclei ; Blazars ;
X-ray astronomy
Abstract:
Among the ∼2157 unassociated sources in the third data release (DR3)
of the fourth Fermi catalog, ∼1200 were observed with the Neil Gehrels
Swift Observatory pointed instruments. These observations yielded
238 high signal-to-noise ratio X-ray sources within the 95% Fermi
uncertainty regions. Recently, Kerby+ (2021, J/ApJ/923/75) employed
neural networks to find blazar candidates among these 238 X-ray
counterparts to the 4FGL unassociated sources and found 112 likely
blazar counterpart sources. A complete sample of blazars, along with
their subclassification, is a necessary step to help understand the
puzzle of the blazar sequence and for the overall completeness of the
gamma-ray emitting blazar class in the Fermi catalog. We employed a
multi-perceptron neural network classifier to identify flat spectrum
radio quasars (FSRQs) and BL Lac objects among these 112 blazar
candidates using the gamma-ray, X-ray, UV/optical, and IR properties.
This classifier provided probability estimates for each source to be
associated with one or the other category, such that Pfsrq represents
the probability for a source to be associated with the FSRQ subclass.
Using this approach, four FSRQs and 50 BL Lac objects are classified
as such with >99% confidence, while the remaining 58 blazars could not
be unambiguously classified as either BL Lac objects or FSRQs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 65 1098 The 1098 sources used for training data containing
BL Lacs and Flat Spectrum Radio Quasars
table2.dat 93 113 The source sample: the 112 blazar candidates
obtained from Kerby+ (2021, J/ApJ/923/75)
table3.dat 100 112 The association results based on the neural network
probabilities for all the 4FGL unassociated sources
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See also:
B/sb9 : SB9: 9th Catalog of Spectroscopic Binary Orbits (Pourbaix+ 2004-2014)
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
II/328 : AllWISE Data Release (Cutri+ 2013)
IX/67 : Incremental Fermi LAT 4th source cat. 4FGL-DR3 (Fermi-LAT col., 2022)
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
J/ApJ/715/429 : First Fermi-LAT AGN catalog (1LAC) (Abdo+, 2010)
J/AcA/62/67 : ASAS photometry of ROSAT sources (Kiraga, 2012)
J/A+A/538/A26 : BL Lac objects beyond z=1.3 (Rau+, 2012)
J/A+A/548/A99 : XMM-Newton Slew Survey in 2-10keV (Warwick+, 2012)
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/ApJ/797/82 : Brightest cluster galaxies in Abell clusters (Lauer+, 2014)
J/MNRAS/470/1291 : Classifying 3FGL with ANN (Salvetti+, 2017)
J/A+A/632/A77 : 3HSP blazars catalog (Chang+, 2019)
J/ApJ/887/134 : Classif. of Fermi blazar cand. from the 4FGL (Kang+, 2019)
J/ApJ/887/18 : Classif. of X-ray counterparts of 3FGL sources (Kaur+, 2019)
J/MNRAS/493/1926 : 4FGL blazar classification neural network (Kovacevic+, 2020)
J/ApJ/923/75 : X-ray/UV/opt xids of 4FGL gamma-ray sources (Kerby+, 2021)
J/ApJS/253/46 : Optical spectroscopy of Fermi blazars (Paliya+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Type Source type ("BL Lacs" or "FSRQ")
9- 20 A12 --- 4FGL Fermi 4FGL catalog identifier (JHHMM.m+DDMM)
22- 27 F6.2 [mW/m2] logFg [-12.16/-9] Log Gamma-ray flux; erg/s/cm2
29- 32 F4.2 --- Gamma [1.45/3.1] The Gamma-ray photon index
34- 38 F5.2 --- Var [-4/1.61] Year-over-year Gamma-ray
variability index
40- 43 F4.2 --- Curve [0.27/4.9] Significance of the curvature in
Gamma-ray spectrum
45- 49 F5.2 [-] logFX/Fg [-2.76/1.27] Log X-ray to Gamma-ray flux
51- 55 F5.2 [-] logFV/Fg [-7.44/-2.66] Log V band to Gamma-ray flux
57- 60 F4.2 mag W1-W2 [0.05/1.51] WISE (W1-W2) color index
62- 65 F4.2 mag W2-W3 [0.7/5.26] WISE (W2-W3) color index
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- 4FGL Fermi 4FGL catalog identifier (JHHMM.m+DDMM)
14- 29 A16 --- SwXF4 Swift/XRT SwXF4 identifier (JHHMMSS.s+DDMMSS)
31- 46 A16 --- SwUVF4 Swift/UVOT SwUVF4 identifier
(JHHMMSS.s+DDMMSS)
48- 53 F6.2 [mW/m2] logFg [-12.14/-10.19] Log Gamma-ray flux;
erg/s/cm2
55- 58 F4.2 --- Gamma [1.69/3.1] The Gamma-ray photon index
60- 64 F5.2 --- Var [-4/0.73] Year-over-year Gamma-ray
variability index
66- 69 F4.2 --- Curve [0.48/1.9] Significance of the curvature in
Gamma-ray spectrum
71- 75 F5.2 [-] logFX/Fg [-1.66/3.2] Log X-ray to Gamma-ray flux
77- 81 F5.2 [-] logFV/Fg [-5.96/-1.9] Log V band to Gamma-ray flux
83- 87 F5.2 mag W1-W2 [-0.09/1.2] WISE (W1-W2) color index
89- 93 F5.2 mag W2-W3 [-0.17/3.31]? WISE (W2-W3) color index
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1 A1 --- RType Result type code (1)
3- 14 A12 --- 4FGL Fermi 4FGL catalog identifier (JHHMM.m+DDMM)
16 A1 --- f_4FGL [b] Flag on 4FGL (2)
18- 33 A16 --- SwUVF4 Swift/UVOT SwUVF4 identifier
(JHHMMSS.s+DDMMSS)
35- 39 F5.3 --- Pfsrq [0.006/0.993] Probability source is an FSRQ
41- 71 A31 --- SType Source type from SIMBAD/SDSS
73- 77 F5.3 --- z [0.05/1.66]? Redshift
78-100 A23 --- r_z Reference and/or flag for z (3)
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Note (1): Code as follows:
A = FSRQ candidates from neural network (NN) results (4 occurrences)
B = BL Lac candidates from NN results (50 occurrences)
C = ambiguous candidates from NN results (58 occurrences)
Note (2): Flag as follows:
b = This source is classified as binary source in the most recent
third data release 4FGL catalog (4FGL-DR3) (Abdollahi+ 2022, IX/67)
Note (3): Reference and flag as follows:
* = The redshift values provided by the SDSS-DR16 and SIMBAD catalogs are
different; 0.94 and 2.14 respectively. In addition, the redshift
estimate has varied from 0.5 to 2.14 in different data releases for
SDSS. The value provided in this table corresponds to the latest data
release, DR16.
ph = photometric redshift from the High-Synchrotron Peaked blazars catalog
by Chang+ (2019A&A...643A..88C 2019A&A...643A..88C).
Krogager et al. (2018) = 2018ApJS..235...10K 2018ApJS..235...10K
Chang et al. (2019) = 2019A&A...643A..88C 2019A&A...643A..88C
Warwick et al. (2012) = 2012A&A...584A..99W 2012A&A...584A..99W
Pourbaix et al. (2004) = 2004A&A...424..727P 2004A&A...424..727P
Jones et al. (2009) = 2009MNRAS.399..683J 2009MNRAS.399..683J; see B/sb9
Kiraga (2012) = 2012, J/AcA/62/67
Lauer et al. (2014) = 2014, J/ApJ/797/82
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Jan-2025