H.E.S.S. discovery of very high energy gamma-ray emission from PKS 0625-354

Abstract

PKS 0625-354 (z=0.055) was observed with the four H.E.S.S. telescopes in 2012 during 5.5 hours. The source was detected above an energy threshold of 200 GeV at a significance level of 6.1$\sigma$. No significant variability is found in these observations. The source is well described with a power-law spectrum with photon index $\Gamma =2.84\pm 0.50_{stat}\pm 0.10_{syst}$ and normalization (at $E_0$=1.0 TeV) $N_0(E_0)=(0.58\pm 0.22_{stat}\pm 0.12_{syst})\times 10^{-12}$ TeV${}^{-1}$cm${}^{-2}$s${}^{-1}$. Multi-wavelength data collected with Fermi-LAT, Swift-XRT, Swift-UVOT, ATOM and WISE are also analysed. Significant variability is observed only in the Fermi-LAT $\gamma$-ray and Swift-XRT X-ray energy bands. Having a good multi-wavelength coverage from radio to very high energy, we performed a broadband modelling from two types of emission scenarios. The results from a one zone lepto-hadronic, and a multi-zone leptonic models are compared and discussed. On the grounds of energetics, our analysis favours a leptonic multi-zone model. Models associated to the X-ray variability constraint supports previous results suggesting a BL Lac nature of PKS 0625-354, with, however, a large-scale jet structure typical of a radio galaxy.

arXiv comment13 pages, 6 figures, accepted for publication in MNRAS

References in corpus (42)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Unified Schemes for Radio-Loud Active Galactic Nuclei
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• A Unified Approach to the Classical Statistical Analysis of Small Signals
• The Swift X-ray Telescope
• The Swift Ultra-Violet/Optical Telescope
• Fermi Large Area Telescope Second Source Catalog
• Fermi Large Area Telescope First Source Catalog
• On characterising the variability properties of X-ray light curves from active galaxies
• The 6dF Galaxy Survey: Final Redshift Release (DR3) and Southern Large-Scale Structures
• Photometric Calibration of the Swift Ultraviolet/Optical Telescope
• Observations of the Crab Nebula with H.E.S.S
• Relations Between Central Black Hole Mass and Total Galaxy Stellar Mass in the Local Universe
• SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. II. The Source Catalogue
• Leptonic and Hadronic Modeling of Fermi-Detected Blazars
• Modeling the Extragalactic Background Light from Stars and Dust
• TeV Gamma Rays from BL Lac Objects due to Synchrotron Radiation of Extremely High Energy Protons
• The Australia Telescope 20 GHz Survey: The Source Catalogue
• A high performance likelihood reconstruction of gamma-rays for Imaging Atmospheric Cherenkov Telescopes
• A hadronic origin for ultra-high-frequency-peaked BL Lac objects
• A Monte Carlo Template based analysis for Air-Cherenkov Arrays
• From the Blazar Sequence to the Blazar Envelope: Revisiting the Relativistic Jet Dichotomy in Radio-loud AGN
• Fermi Large Area Telescope Observations of Misaligned AGN
• Spine-sheath layer radiative interplay in subparsec-scale jets and the TeV emission from M87
• Temporal and spectral gamma-ray properties of Mkn421 above 250 GeV from CAT observations between 1996 and 2000
• The black hole mass of low redshift radiogalaxies
• Swift and infra-red observations of the blazar 3C~454.3 during the giant X-ray flare of May 2005
• TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry I. First-Epoch 8.4 GHz Images
• Detection of very-high energy γ-ray emission from NGC 1275 by the MAGIC telescopes
• Detection of very high energy gamma-ray emission from the Perseus cluster head-tail galaxy IC 310 by the MAGIC telescopes
• Mrk 421 as a case study for TeV and X-ray variability in leptohadronic models
• Emission lines and optical continuum in low-luminosity radio galaxies
• Synchrotron and inverse-Compton emission from blazar jets I: a uniform conical jet model
• VLBI Observations of a Complete Sample of Radio Galaxies. IV-The Radio Galaxies NGC2484, 3C109 and 3C382
• On the spine-layer scenario for the very high-energy emission of NGC 1275
• Linking radio and gamma ray emission in Ap Librae
• A near-IR study of the host galaxies of 2Jy radio sources at 0.03 < z < 0.5: I - the data
• The high-energy $\gamma$-ray emission of AP Librae
• Suzaku Observations of gamma-Ray Bright Radio Galaxies: Origin of the X-ray Emission and Broad-Band Modelin
• The polyhedral nature of LINERs: An XMM-Newton view of LINERs in radio galaxies
• Near infrared and gamma-ray monitoring of TANAMI gamma-ray bright sources

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• Discovery of Very-high-energy Gamma-ray Emissions from the Low Luminosity AGN NGC 4278 by LHAASO
• VERITAS Discovery of VHE Emission from the Radio Galaxy 3C 264: A Multi-Wavelength Study
• High energy emission component, population, and contribution to the extragalactic gamma-ray background of gamma-ray emitting radio galaxies
• A search for Centaurus A-like features in the spectra of Fermi-LAT detected radio galaxies
• A cosmic Zevatron based on cyclotron auto-resonance
• The beaming effect for Fermi-LAT-detected FR-I radio galaxies
• Looking for the possible gluon condensation signature in sub-TeV gamma-ray spectra: from active galactic nuclei to gamma ray bursts
• TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry. III. First-epoch S band images
• Probing IC/CMB Interpretation for the X-ray knots of AGN through VHE observations
• Gamma-ray emission in radio galaxies, from MeV to TeV
• Prospects of additional contribution at Optical-NIR band of EBL in the light of VHE spectra
• The H.E.S.S. extragalactic sky survey with the first decade of observations
• Progress in Multiwavelength and Multi-Messenger Observations of Blazars and Theoretical Challenges