A Very High Energy Gamma-Ray Spectrum of 1ES 2344+514

Abstract

The BL Lacertae (BL Lac) object 1ES 2344+514 (1ES 2344), at a redshift of 0.044, was discovered as a source of very high energy (VHE) gamma rays by the Whipple Collaboration in 1995 \citep{2344Catanese98}. This detection was recently confirmed by the HEGRA Collaboration \citep{2344Hegra03}. As is typical for high-frequency peaked blazars, the VHE gamma-ray emission is highly variable. On the night of 20 December, 1995, a gamma-ray flare of 5.3-sigma significance was detected, the brightest outburst from this object to-date. The emission region is compatible with a point source. The spectrum between 0.8 TeV and 12.6 TeV can be described by a power law $\frac{\ud^3 N}{\ud E \ud A \ud t}=(5.1\pm1.0_{st}\pm1.2_{sy})\times10^{-7} (E/ \mathrm{TeV})^{-2.54 \pm0.17_{st}\pm0.07_{sy}} \mathrm{\frac{1}{TeV m^2 s}}$. Comparing the spectral index with that of the other five confirmed TeV blazars, the spectrum of 1ES 2344 is similar to 1ES 1959+650, located at almost the same distance. The spectrum of 1ES 2344 is steeper than the brightest flare spectra of Markarian 421 (Mrk~421) and Markarian 501 (Mrk~501), both located at a distance about 2/3 that of 1ES 2344, and harder than the spectra of PKS 2155-304 and H~1426+428, which are located almost three times as far. This trend is consistent with attenuation caused by the infrared extragalactic background radiation.

27 pages, 11 figures, accepted by ApJ

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• Ground based gamma-ray astronomy with Cherenkov Telescopes
• Observation of very high energy gamma-rays from the AGN 1ES 2344+514 in a low emission state with the MAGIC telescope
• Synoptic studies of seventeen blazars detected in very high-energy gamma-rays
• Improved limits on Lorentz invariance violation from astrophysical gamma-ray sources
• Multiwavelength Observations of the VHE Blazar 1ES 2344+514
• Constraints on the Extragalactic Background Light from Very High Energy Gamma-Ray Observations of Blazars
• The Simultaneous Low State Spectral Energy Distribution of 1ES 2344+514 from Radio to Very High Energies
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• An intermittent extreme BL Lac: MWL study of 1ES 2344+514 in an enhanced state
• Very-High-Energy $\gamma$-Ray Observations of the Blazar 1ES 2344+514 with VERITAS
• Spectral Energy Distributions for TeV Blazars
• Astrophysics in 2006
• Exploring TeV candidates of Fermi blazars through machine learning
• Photohadronic interpretation of the different incarnation of 1ES 2344+514
• Observations of Extragalactic Sources with the MAGIC Telescope
• High-(Energy)-Lights -- The Very High Energy Gamma-Ray Sky
• Status of Very High Energy gamma-ray Astronomy as of early 2008
• Studying the Extreme Behaviour of 1ES 2344+51.4
• Broadband Spectral Analysis of 1ES2344+514: A Multi-epoch study
• Statistical Tools for Analyzing the Cosmic Ray Energy Spectrum