J/ApJS/282/35 4FGL very high-energy gamma-ray emitting blazars (Agarwal+, 2026)
Hunting very high-energy-emitting (>100GeV) high-synchrotron-peaked blazars.
Agarwal S., Paliya V.S.
<Astrophys. J. Suppl. Ser., 282, 35 (2026)>
=2026ApJS..282...35A 2026ApJS..282...35A
ADC_Keywords: Active gal. nuclei; BL Lac objects; Gamma rays; Redshifts
Keywords: BL Lacertae objects ; Blazars ; High energy astrophysics ;
Relativistic jets ; Supermassive black holes ; Catalogs
Abstract:
Very high-energy (VHE; >100GeV) γ-ray emission originates via
some of the most extreme particle acceleration processes in the
Universe. Considering beamed active galactic nuclei, i.e., blazars,
only a small fraction, mainly high-synchrotron-peaked BL Lacertae
(BLLac) objects, have been detected in the VHE band with ground-based
Cherenkov telescopes. We utilized ∼16yr of Fermi Large Area Telescope
(LAT) observations in the 0.1-2 TeV energy range to systematically
search for potential VHE emitters in a sample of
high-synchrotron-peaked (νsynpeak>1015Hz) BL Lac sources. We
identified, for the first time, 92 VHE-emitting blazars at a
≥5σ confidence level. A significant VHE emission was also
detected from 52 sources previously reported as VHE blazars. Comparing
with the general blazar population, these VHE-emitting blazars are
found to be located at low redshifts (mean z=0.2±0.1) and exhibit
bright synchrotron emission (logFsynpeak=-11.2±0.4, in
erg/cm2/s). We also investigated the coincidence of VHE photon
arrivals with the source activity states and found that Fermi-LAT has
detected VHE photons during both quiescent and elevated activity
epochs. These VHE-emitting blazars represent promising targets for
current and next-generation ground-based Cherenkov telescopes, and
provide powerful laboratories for probing particle acceleration in
relativistic jets, testing multimessenger connections, and
constraining extragalactic background light models.
Description:
We utilized ∼16yr of Fermi-LAT observations conducted from MJD 54683
to 60587 (2008 August 5 to 2024 October 4).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 137 92 The spectral parameters of the newly identified
VHE-emitting blazars
table2.dat 137 52 The spectral parameters of known VHE-emitting
blazars in TeVCAT
table3.dat 72 116 Sources with test statistics (TS) between 12 and 25
table4.dat 28 196 The remaining HSP Blazars with TS<12 and
at least one VHE photon detected with more
than 95% probability of association
table5.dat 28 10 Unassociated Fermi sources where at least one
VHE photon was detected
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Description of files:
HSP_VHE.fits is the original FITS file with 5 HDU as downloaded at:
https://zenodo.org/records/17593405
See also:
IX/67 : Incremental Fermi LAT 4th source cat. (4FGL-DR3) (Fermi-LAT col., 2022)
IX/72 : Fermi LAT Fourth Source Cat. DR4 (4FGL-DR4) (Ballet+, 2023)
J/ApJ/716/30 : SED of Fermi bright blazars (Abdo+, 2010)
J/A+A/541/A160 : Planck + X/γ observations of blazars (Giommi+, 2012)
J/ApJ/764/135 : Spectroscopic redshifts of BL Lac objects (Shaw+, 2013)
J/A+A/579/A34 : 1WHSP: VHE γ-ray blazar candidates (Arsioli+, 2015)
J/A+A/598/A134 : gamma-ray signature in WHSP blazars (1BIGB) (Arsioli+, 2017)
J/A+A/598/A17 : The 2WHSP catalog (Chang+, 2017)
J/A+A/632/A77 : 3HSP blazars catalog (Chang+, 2019)
J/ApJS/248/29 : Simultaneous X-ray & gamma obs. of Mrk421 (Acciari+, 2020)
J/ApJS/253/46 : Optical spectroscopy of Fermi blazars (Paliya+, 2021)
J/ApJS/263/24 : The 4LAC-DR3 catalog (Ajello+, 2022)
J/ApJS/261/2 : BASS. XXII. Swift/BAT AGN Sp. Survey DR2 cat. (Koss+, 2022)
J/MNRAS/539/1458 : 1st Cosmic Gamma-Ray Horizon Catalog, 1CGH (Arsioli+, 2025)
http://www.tevcat.org/ : Online TeVCat catalog
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- 4FGL 4FGL source name (JHHMM.m+DDMM)
14- 21 F8.3 --- z [0.03/0.6]? Spectroscopic redshift of the
source (1)
23- 26 I4 --- TSobs [25/6308] Observed TS
28- 39 E12.6 MeV/cm^2/s Fobs [2.2e-07/0.0002] Observed energy flux in
10-6MeV/cm2/s
41- 52 E12.6 MeV/cm^2/s e_Fobs [1.4e-07/1.1e-05] Fobs uncertainty
54- 58 F5.2 --- GamObs [1.5/10] Observed photon index, in the
energy range of 0.1-2TeV
60- 63 F4.2 --- e_GamObs [0/4.2] GamObs uncertainty
65- 68 I4 --- TSebl [25/6309]? EBL-attenuation-corrected TS (2)
70- 80 F11.6 MeV/cm^2/s Febl [0/0.0002]? EBL-attenuation-corrected
energy flux in 10-6MeV/cm2/s (2)
82- 92 F11.6 MeV/cm^2/s e_Febl [0/1.1e-05]? Febl uncertainty
94- 105 E12.6 --- GamEBL [0/10]? EBL-attenuation-corrected photon
index, in the energy range of 0.1-2TeV (2)
107- 118 E12.6 --- e_GamEBL [0.01/4.3]? GamEBL uncertainty
120- 122 I3 --- Nvhe [2/375] Number of >100GeV photons detected
from the source having ≥95% association
probability
124- 129 F6.1 GeV Emax [114.3/1726.5] Energy of the maximum
energy photons
131- 137 F7.1 d MJD [54696.5/60584.6] Time of arrival of the
maximum energy photons
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Note (1): Spectroscopic redshift of the source from
Arsioli+ (2025MNRAS.539.1458A 2025MNRAS.539.1458A) and Paliya+ (2025ApJ...991L...8P 2025ApJ...991L...8P)
Note (2): Only listed for sources with available spectroscopic redshift
measurement
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- 4FGL 4FGL source name (JHHMM.m+DDMM)
14- 15 I2 --- TSobs [12/24] Observed TS
17- 28 E12.6 MeV/cm^2/s Fobs [1.3e-07/2.71e-06] Observed energy flux in
10-6MeV/cm2/s
30- 41 E12.6 MeV/cm^2/s e_Fobs [9e-08/2.1e-06] Fobs uncertainty
43- 47 F5.2 --- GamObs [0.8/10] Observed photon index, in the
energy range of 0.1-2TeV
49- 52 F4.2 --- e_GamObs [0/4.9] GamObs uncertainty
54- 56 F3.1 --- f_GamObs [0/1] Flag on GamObs
(1=sources with GamObs=10)
58 I1 --- Nvhe [1/5] Number of >100GeV photons detected
from the source having ≥95% association
probability
60- 64 F5.1 GeV Emax [100.1/712.7] Energy of the maximum energy
photons
66- 72 F7.1 d MJD [54699/60552.1] Time of arrival of the
maximum energy photons
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Byte-by-byte Description of file: table[45].dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- 4FGL 4FGL source name (JHHMM.m+DDMM)
14 I1 --- Nvhe [1/2] Number of >100GeV photons detected from the
source having ≥95% association probability
16- 20 F5.1 GeV Emax [100.3/756.6] Energy of the maximum energy photons
22- 28 F7.1 d MJD [54682.8/60583.9] Time of arrival of the maximum
energy photons
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History:
Downloaded at: https://zenodo.org/records/17593405
(doi:10.5281/zenodo.17593405)
License: CC-BY-4.0
(End) Emmanuelle Perret [CDS] 21-Jul-2026