J/MNRAS/480/2165 The γ-ray spectrum of 1BIGB sources (Arsioli+, 2018)
Extreme- and high-synchrotron-peaked blazars at the limit of Fermi-LAT
detectability: the γ-ray spectrum of 1BIGB sources.
Arsioli B., Barres de Almeida U., Prandini E., Fraga B., Foffano L.
<Mon. Not. R. Astron. Soc., 480, 2165-2177 (2018)>
=2018MNRAS.480.2165A 2018MNRAS.480.2165A (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; BL Lac objects ; Gamma rays ; Galaxies
Keywords: radiation mechanisms: non-thermal - galaxies: active -
BL Lacertae objects: general - gamma-rays: galaxies
Abstract:
We present the 1-100GeV spectral energy distribution (SED) for a
population of 148 high-synchrotron-peaked (HSP) blazars recently
detected with Fermi-LAT as part of the First Brazil-ICRANet Gamma-ray
Blazar (1BIGB) catalogue. Most of the 1BIGB sources have their
γ-ray spectral properties presented here for the first time,
representing a significant new extension of the γ-ray blazar
population. Since our sample was originally selected from an excess
signal in the 0.3-500GeV band, the sources stand out as promising TeV
blazar candidates, potentially in reach of the forthcoming very high
energy (VHE) γ-ray observatory, Cherenkov Telescope Array (CTA).
The flux estimates presented here are derived considering PASS8 data,
integrating over more than 9yr of Fermi-LAT observations. We also
review the full broad-band fit between 0.3 and 500GeV presented in the
original 1BIGB paper for all sources, updating the power-law
parameters with currently available Fermi-LAT data set. The importance
of these sources in the context of VHE population studies with both
current instruments and the future CTA is evaluated. To do so, we
select a subsample of 1BIGB sources and extrapolate their γ-ray
SEDs to the highest energies, properly accounting for absorption due
to the extragalactic background light. We compare those extrapolations
to the published CTA sensitivity curves and estimate their
detectability by CTA. Two notable sources from our sample, namely
1BIGBJ224910.6-130002 and 1BIGBJ194356.2+211821, are discussed in
greater detail. All γ-ray SEDs are made publicly available via
the Brazilian Science Data Center (BSDC) service, maintained at CBPF,
in Rio de Janeiro.
Description:
The 1BIGB sample (Arsioli & Chang, 2017A&A...598A.134A 2017A&A...598A.134A, Cat.
J/A+A/598/A134) was built based on the selection of 400 γ-ray
candidates from the 1WHSP and 2WHSP samples.
The 1BIGB detections considered a broad-band likelihood analysis
between 0.3 and 500GeV, integrating data from 2008 August 04 up to
2015 November 04 (∼7.2yr). Since that time, Fermi-LAT has accumulated
more than two additional years of observation time (at the time of
writing, we have available data up to 2017 December 05). Taking
advantage of a larger exposure time with Fermi-LAT, we thus refine the
power-law fitting for each 1BIGB source by performing a likelihood
analysis similar to Arsioli & Chang (2017A&A...598A.134A 2017A&A...598A.134A), applying
the same set-up and data quality cuts.
Table A1 lists the model description for 148 cases that had good
convergence.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 111 148 Table showing the 148 1BIGB γ-ray signatures
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See also:
J/A+A/598/A134 : γ-ray signature in WHSP blazars (1BIGB) (Arsioli+, 2017)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 21 A21 --- Name 1BIGB source name
(1BIGBJHHMMSS.s+DDMMSS)
23- 31 F9.5 deg RAdeg Right ascension (J2000)
33- 41 F9.5 deg DEdeg Declination (J2000)
43 A1 --- l_z Limit flag on the redshift
45- 49 F5.3 --- z ? Redshift (1)
51 A1 --- f_z Flag on the redshift (2)
53- 56 F4.2 --- GAMMA Spectral photon index (3)
58- 61 F4.2 --- e_GAMMA Error on spectral photon index
63- 67 F5.2 10-15ph/cm2/s/MeV N0 Prefactor corresponding to the flux
density at the pivot energy E0 (3)
69- 72 F4.2 10-15ph/cm2/s/MeV e_N0 Error on N0
74- 80 F7.1 --- TS Test statistics (TS, Mattox et al.
1996ApJ...461..396M 1996ApJ...461..396M)
82- 86 F5.2 10-10ph/cm2/s Flux Photon counts (4)
88- 91 F4.2 10-10ph/cm2/s E_Flux Upper error on photon counts
93- 96 F4.2 10-10ph/cm2/s e_Flux Lower error on photon counts
98-102 F5.1 MeV/cm2/s EFlux Energy flux
104-107 F4.1 MeV/cm2/s E_EFlux Energy flux
109-111 F3.1 MeV/cm2/s e_EFlux Energy flux
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Note (1): Sources with currently absent redshift were given 0 value.
Note (2): Flag as follows:
? = used for values reported as uncertain
Note (3): Parameters Γ and N0 are direct outputs from the likelihood
analysis over 7.2yr of Fermi-LAT data in the 0.3-500GeV band; those
results consider the pivot energy fixed as E0=1GeV.
Note (4): Photon counts are calculated by integrating equation
dN/dE=N0.(E/E0)-Γ along the energy range of 1-100GeV.
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 19-May-2022