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Title: The high-energy γ -ray emission of AP Librae

Journal Article · · Astronomy and Astrophysics
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In this paper, the γ-ray spectrum of the low-frequency-peaked BL Lac (LBL) object AP Librae is studied, following the discovery of very-high-energy (VHE; E> 100 GeV) γ-ray emission up to the TeV range by the H.E.S.S. experiment. This makes AP Librae one of the few VHE emitters of the LBL type. The measured spectrum yields a flux of (8.8 ± 1.5stat ± 1.8sys) × 10-12 cm-2 s-1 above 130 GeV and a spectral index of Γ = 2.65 ± 0.19stat ± 0.20sys. This study also makes use of Fermi-LAT observations in the high energy (HE, E> 100 MeV) range, providing the longest continuous light curve (5 years) ever published on this source. The source underwent a flaring event between MJD 56 306–56 376 in the HE range, with a flux increase of a factor of 3.5 in the 14 day bin light curve and no significant variation in spectral shape with respect to the low-flux state. While the H.E.S.S. and (low state) Fermi-LAT fluxes are in good agreement where they overlap, a spectral curvature between the steep VHE spectrum and the Fermi-LAT spectrum is observed. Finally, the maximum of the γ-ray emission in the spectral energy distribution is located below the GeV energy range.

Research Organization:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Organization:
USDOE
Contributing Organization:
H.E.S.S. Collaboration
Grant/Contract Number:
AC02-76SF00515
OSTI ID:
1355171
Journal Information:
Astronomy and Astrophysics, Vol. 573; ISSN 0004-6361
Publisher:
EDP SciencesCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 12 works
Citation information provided by
Web of Science

References (52)

The redshift and composite nature of AP Librae /PKS 1514-24/ journal December 1974
The connection between x-ray- and radio-selected BL Lacertae objects journal May 1995
Black Hole Masses and Host Galaxy Evolution of Radio‐Loud Active Galactic Nuclei journal October 2005
Discovery of Very High Energy γ-Ray Emission from the Low-Frequency-peaked BL Lacertae Object BL Lacertae journal August 2007
Spectroscopy of the Largest ever γ-Ray-Selected bl lac Sample journal January 2013
FERMI LARGE AREA TELESCOPE DETECTION OF BRIGHT γ-RAY OUTBURSTS FROM THE PECULIAR QUASAR 4C +21.35 journal April 2011
THE SECOND CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE journal December 2011
A Search for Very High Energy Gamma Rays from Active Galactic Nuclei Visible from the Southern Hemisphere journal August 1999
FERMI OBSERVATIONS OF TeV-SELECTED ACTIVE GALACTIC NUCLEI journal December 2009
Compact Extragalactic Nonthermal Sources journal July 1972
Synchrotron Self‐Compton Analysis of TeV X‐Ray‐Selected BL Lacertae Objects journal October 2008
FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG journal March 2012
PKS 1502+106: A NEW AND DISTANT GAMMA-RAY BLAZAR IN OUTBURST DISCOVERED BY THE FERMI LARGE AREA TELESCOPE journal January 2010
The Likelihood Analysis of EGRET Data journal April 1996
The 2010 very high Energy γ-Ray Flare and 10 Years of Multi-Wavelength Observations of m 87 journal February 2012
Temporal and spectral gamma-ray properties of Mkn 421 above 250 GeV from CAT observations between 1996 and 2000 journal August 2001
An Exceptional Very High Energy Gamma-Ray Flare of PKS 2155-304 journal July 2007
Surveys with the Cherenkov Telescope Array journal March 2013
A high performance likelihood reconstruction of γ-rays for imaging atmospheric Cherenkov telescopes journal December 2009
Rapid Optical Variability of the Source PKS 1514–24 journal July 1971
Background modelling in very-high-energy γ -ray astronomy journal April 2007
BRIGHT ACTIVE GALACTIC NUCLEI SOURCE LIST FROM THE FIRST THREE MONTHS OF THE FERMI LARGE AREA TELESCOPE ALL-SKY SURVEY journal July 2009
TeV BL Lac objects at the dawn of the Fermi era journal January 2010
The Third EGRET Catalog of High‐Energy Gamma‐Ray Sources journal July 1999
Discovery of an Extended X-Ray jet in ap Librae journal September 2013
Extragalactic optical-infrared background radiation, its time evolution and the cosmic photon-photon opacity journal June 2008
Modeling the Extragalactic Background Light from Stars and dust journal February 2010
A unifying view of the spectral energy distributions of blazars journal September 1998
Studies of BL Lacertae objects with the Einstein X-ray observatory - The absolute volume density journal March 1983
Discovery of VHE γ -ray emission and multi-wavelength observations of the BL Lacertae object 1RXS J101015.9 − 311909 journal June 2012
THE LARGE AREA TELESCOPE ON THE FERMI GAMMA-RAY SPACE TELESCOPE MISSION journal May 2009
Evidence for a cosmological effect in γ -ray spectra of BL Lacertae journal June 2013
Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with H.E.S.S. journal January 2013
Constraints on the Physical Parameters of TeV Blazars journal December 1998
A Radio Reference Frame journal August 1995
FERMI /LARGE AREA TELESCOPE BRIGHT GAMMA-RAY SOURCE LIST journal June 2009
GAMMA-RAY LIGHT CURVES AND VARIABILITY OF BRIGHT FERMI -DETECTED BLAZARS journal September 2010
Observations of the Crab nebula with HESS journal September 2006
The University of Durham Mark 6 Gamma Ray Telescope journal January 1999
Magic Discovery of very high Energy Emission from the fsrq pks 1222+21 journal February 2011
Analysis methods for results in gamma-ray astronomy journal September 1983
The 6dF Galaxy Survey: final redshift release (DR3) and southern large-scale structures journal October 2009
The Crab Nebula as a standard candle in very high-energy astrophysics journal November 2010
On characterizing the variability properties of X-ray light curves from active galaxies journal November 2003
Discovery of very high Energy γ-Rays from the Blazar s5 0716+714 journal October 2009
The Parkes Catalogue of Radio Sources Declination Zone ?20° to ?60° journal January 1964
Rapid X‐Ray Variability of the BL Lacertae Object PKS 2155−304 journal December 1999
THE SPECTRAL ENERGY DISTRIBUTION OF FERMI BRIGHT BLAZARS journal May 2010
THE FERMI LARGE AREA TELESCOPE ON ORBIT: EVENT CLASSIFICATION, INSTRUMENT RESPONSE FUNCTIONS, AND CALIBRATION journal October 2012
Unified approach to the classical statistical analysis of small signals journal April 1998
The Optically Variable Radio Source PKS 1514-24 = AP Librae journal July 1971
FERMI GAMMA-RAY SPACE TELESCOPE OBSERVATIONS OF GAMMA-RAY OUTBURSTS FROM 3C 454.3 IN 2009 DECEMBER AND 2010 APRIL journal September 2010

Cited By (6)

GeV-TeV γ $\gamma $ -ray energy spectral break of BL Lac objects journal August 2018
The CGM and IGM at z ∼ 5: metal budget and physical connection journal September 2018
H.E.S.S. discovery of very high energy γ-ray emission from PKS 0625−354 journal February 2018
Megaparsec-scale Radio Structure Associated with a Hybrid Blazar SBS B1646+499: Episodic Jet Activity with Precessing Axis journal November 2018
H.E.S.S. discovery of very high energy $\gamma$-ray emission from PKS 0625-354 text January 2018
Megaparsec-scale Radio Structure Associated with a Hybrid Blazar SBS B1646+499: Episodic Jet Activity with Precessing Axis text January 2018

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Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
galaxies
active / BL Lacertae objects
individual
AP Librae / gamma rays