The high-frequency-peaked BL Lac (HBL) 1ES 0806+524 (z =0.138) was discovered in very high energy (VHE) γ-rays in 2008. Until now, the broad-band spectrum of 1ES 0806+524 has been only poorly characterized, in particular at high energies. We analysed multiwavelength observations from γ-rays to radio performed from 2011 January to March, which were triggered by the high activity detected at optical frequencies. These observations constitute the most precise determination of the broad-band emission of 1ES 0806+524 to date. The stereoscopic Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) observations yielded a γ-ray signal above 250 GeV of (3.7 ± 0.7) per cent of the Crab Nebula flux with a statistical significance of 9.9σ. The multiwavelength observations showed significant variability in essentially all energy bands, including a VHE γ-ray flare that lasted less than one night, which provided unprecedented evidence for short-term variability in 1ES 0806+524. The spectrum of this flare is well described by a power law with a photon index of 2.97 ± 0.29 between ~150 GeV and 1 TeV and an integral flux of (9.3 ± 1.9) per cent of the Crab nebula flux above 250 GeV. The spectrum during the non-flaring VHE activity is compatible with the only available VHE observation performed in 2008 with VERITAS when the source was in a low optical state. The broad-band spectral energy distribution can be described with a one-zone synchrotron self-Compton model with parameters typical for HBLs, indicating that 1ES 0806+524 is not substantially different from the HBLs previously detected.
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|Titolo:||MAGIC detection of short-term variability of the high-peaked BL Lac object 1ES 0806+524|
|Citazione:||Aleksić, J., Ansoldi, S., Antonelli, L.A., Antoranz, P., Babic, A., Bangale, P., et al. (2015). MAGIC detection of short-term variability of the high-peaked BL Lac object 1ES 0806+524. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 451(1), 739-750.|
|Appare nelle tipologie:||1.1 Articolo in rivista|
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