VHE $\gamma$-ray discovery and multi-wavelength study of the blazar 1ES 2322-409

Abstract

A hotspot at a position compatible with the BL Lac object 1ES 2322-409 was serendipitously detected with H.E.S.S. during observations performed in 2004 and 2006 on the blazar PKS 2316-423. Additional data on 1ES 2322-409 were taken in 2011 and 2012, leading to a total live-time of 22.3h. Point-like very-high-energy (VHE; E>100GeV) $\gamma$-ray emission is detected from a source centred on the 1ES 2322-409 position, with an excess of 116.7 events at a significance of 6.0$\sigma$. The average VHE $\gamma$-ray spectrum is well described with a power law with a photon index $\Gamma =3.40\pm 0.66_{\text{stat}}\pm 0.20_{\text{sys}}$ and an integral flux $\Phi (E>200GeV)=(3.11\pm 0.71_{\mathrm{stat}}\pm 0.62_{\mathrm{sys}})\times 10^{-12}c{m}^{-2}{s}^{-1}$, which corresponds to 1.1$\%$ of the Crab nebula flux above 200 GeV. Multi-wavelength data obtained with Fermi LAT, Swift XRT and UVOT, RXTE PCA, ATOM, and additional data from WISE, GROND and Catalina, are also used to characterise the broad-band non-thermal emission of 1ES 2322-409. The multi-wavelength behaviour indicates day-scale variability. Swift UVOT and XRT data show strong variability at longer scales. A spectral energy distribution (SED) is built from contemporaneous observations obtained around a high state identified in Swift data. A modelling of the SED is performed with a stationary homogeneous one-zone synchrotron-self-Compton (SSC) leptonic model. The redshift of the source being unknown, two plausible values were tested for the modelling. A systematic scan of the model parameters space is performed, resulting in a well-constrained combination of values providing a good description of the broad-band behaviour of 1ES 2322-409.

arXiv commentAccepted for publication in MNRAS. 13 pages, 8 figures

References in corpus (31)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Swift X-ray Telescope
• The Swift Ultra-Violet/Optical Telescope
• First Results from the Catalina Real-time Transient Survey
• The 6dF Galaxy Survey: Final Redshift Release (DR3) and Southern Large-Scale Structures
• Photometric Calibration of the Swift Ultraviolet/Optical Telescope
• The extragalactic optical-infrared background radiations, their time evolution and the cosmic photon-photon opacity
• The GMRT 150 MHz All-sky Radio Survey: First Alternative Data Release TGSS ADR1
• Observations of the Crab Nebula with H.E.S.S
• SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. II. The Source Catalogue
• Calibration of X-ray absorption in our Galaxy
• GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
• The Las Campanas Redshift Survey
• Constraints on the Physical Parameters of TeV Blazars
• Development of the Model of Galactic Interstellar Emission for Standard Point-Source Analysis of Fermi Large Area Telescope Data
• GROND - a 7-channel imager
• 3FHL: The Third Catalog of Hard Fermi-LAT Sources
• Background Modelling in Very-High-Energy gamma-ray Astronomy
• GLEAM: The GaLactic and Extragalactic All-sky MWA survey
• TeV BL Lac objects at the dawn of the Fermi era
• A Monte Carlo Template based analysis for Air-Cherenkov Arrays
• The SEDs and Host Galaxies of the dustiest GRB afterglows
• Pass 8: Toward the Full Realization of the Fermi-LAT Scientific Potential
• Temporal and spectral gamma-ray properties of Mkn421 above 250 GeV from CAT observations between 1996 and 2000
• The First Swift Ultra-Violet/Optical Telescope GRB Afterglow Catalog
• H.E.S.S. discovery of VHE gamma-rays from the quasar PKS 1510-089
• BL Lacertae objects beyond redshift 1.3 - UV-to-NIR photometry and photometric redshift for Fermi/LAT blazars
• A new analysis strategy for detection of faint gamma-ray sources with Imaging Atmospheric Cherenkov Telescopes
• Break in the VHE spectrum of PG 1553+113: new upper limit on its redshift?
• Upper Limits from HESS AGN Observations in 2005-2007
• H.E.S.S and Fermi-LAT discovery of gamma rays from the blazar 1ES 1312-423

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