J/ApJ/954/194 Bright gamma-ray blazars among the 4LAC (Yoshida+, 2023)
Flare duty cycle of gamma-ray blazars and implications for high-energy neutrino
emission.
Yoshida K., Petropoulou M., Murase K., Oikonomou F.
<Astrophys. J., 954, 194 (2023)>
=2023ApJ...954..194Y 2023ApJ...954..194Y
ADC_Keywords: Gamma rays; Active gal. nuclei; Neutrino; Redshifts; Optical
Keywords: Blazars ; Gamma-ray astronomy ; High energy astrophysics ;
Neutrino astronomy
Abstract:
Gamma-ray flares of blazars may be accompanied by high-energy
neutrinos due to interactions of high-energy cosmic rays in the jet
with photons, as suggested by the detection of the high-energy
neutrino IceCube-170922A during a major gamma-ray flare from blazar
TXS 0506+056 at the ∼3σ significance level. In this work, we
present a statistical study of gamma-ray emission from blazars to
constrain the contribution of gamma-ray flares to their neutrino
output. We construct weekly binned light curves for 145 gamma-ray
bright blazars in the Fermi Large Area Telescope Monitored Source List
adding TXS 0506+056. We derive the fraction of time spent in the
flaring state (flare duty cycle) and the fraction of energy released
during each flare from the light curves with a Bayesian blocks
algorithm. We find that blazars with lower flare duty cycles and
energy fractions are more numerous among our sample. We identify a
significant difference in flare duty cycles between blazar subclasses
at a significance level of 5%. Then using a general scaling relation
for the neutrino and gamma-ray luminosities,
Lν∝(Lγ)γ with a weighting exponent of
γ=1.0-2.0, normalized to the quiescent gamma-ray or X-ray flux
of each blazar, we evaluate the neutrino energy flux of each gamma-ray
flare. The gamma-ray flare distribution indicates that blazar neutrino
emission may be dominated by flares for γ≳1.5. The neutrino
energy fluxes for 1 week and 10 yr bins are compared with the
decl.-dependent IceCube sensitivity to constrain the standard neutrino
emission models for gamma-ray flares. Finally, we present the
upper-limit contribution of blazar gamma-ray flares to the isotropic
diffuse neutrino flux.
Description:
We select 145 gamma-ray bright blazars (Table A1), consisting of 106
flat spectrum radio quasars (FSRQs), 31 BL Lac objects, and 8 blazar
candidates of uncertain type (BCUs). Among them, 144 blazars are
selected from the Fermi LAT Monitored Source List, which we identified
as blazars with the Fourth Catalog of AGN detected by the LAT
(4LAC-DR2, Ajello+ 2020, J/ApJ/892/105) and one is TXS 0506+056.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
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05 09 25.96 +05 41 35.3 TXS 0506+056 = QSO J0509+0541
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 73 145 List of our sources
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See also:
J/ApJ/743/171 : The 2LAC catalog (Ackermann+, 2011)
J/ApJ/846/34 : Flaring gamma-ray sources; LAT 7.4yr (2FAV) (Abdollahi+, 2017)
J/ApJ/864/84 : Swift follow-up obs. of TXS 0506+056 (Keivani+, 2018)
J/ApJS/247/33 : The Fermi LAT fourth source catalog (4FGL) (Abdollahi+, 2020)
J/ApJ/892/105 : Fourth cat. of Fermi LAT-detected AGNs (4LAC) (Ajello+, 2020)
J/A+A/650/A83 : Radio flux densities of neutrino associations (Hovatta+, 2021)
http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/ : Fermi LAT Monitored
Source List
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [4FGL]
6- 17 A12 --- 4FGL The 4LAC catalog identifier
(Ajello+ 2020, J/ApJ/892/105)
19- 37 A19 --- Name Object name
39- 46 F8.4 deg RAdeg Right Ascension (J2000)
48- 55 F8.4 deg DEdeg [-83.7/78.5] Declination (J2000)
57- 60 A4 --- OptCl Optical class (1)
62- 64 A3 --- sedCl SED class from Ajello+ 2020, J/ApJ/892/105
66- 73 F8.6 --- z [0.03/3.2]? Spectroscopic derived redshift (2)
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Note (1): Optical class from the 4LAC (Ajello+ 2020, J/ApJ/892/105) as follows:
FSRQ = Flat spectrum radio quasar (106 occurrences)
BLL = BL Lac object (31 occurrences)
BCU = Blazar candidates of uncertain type (8 occurrences)
Note (2): Redshifts are from the 4LAC and SIMBAD.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Oct-2025