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Long-term study of the intermittent extreme behaviour of 1ES 2344+514
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A4 Artikkeli konferenssijulkaisussa
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Authors
Arbet Engels, A.
Mondal, H. A.
Fukami, S.
D’Ammando, F.
Dorner, D.
Chatterjee, R.
Majumdar, P.
Manganaro, M.
Hovatta, T.
Das, S.
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en
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POS Proceedings of Science, Volume 444
Abstract
Extreme high-frequency-peaked BL Lac objects (EHBLs) are the most energetic persistent sources in the Universe. They are characterized by a spectral energy distribution (SED) featuring a synchrotron peak energy above 1 keV. 1ES 2344+514 is a blazar known to behave as an EHBL intermittently. Until now, its EHBL nature was only reported during flares, but a coherent picture is missing as unbiased monitoring campaigns are lacking. This work presents the longest observing campaign from radio to very-high-energy (VHE) frequencies performed so far on 1ES2344+514. Using observations during 2019-2021, we carry out a systematic investigation of the intermittent EHBL phases. Together with MAGIC, the dataset also includes X-ray observations from NuSTAR, XMM-Newton, and AstroSAT, providing an unprecedented determination of the two SED components. For the first time we report a clear EHBL behaviour during a low flux activity in 1ES 2344+514. It implies a significant hardening of the electron distribution inside the jet independent of flux. We also detect a bright X-ray state characterized by an unusually soft spectra, thus violating the harder-when-brighter relation typically found in blazars. The SED study further reveals an excess in the ultraviolet data with respect to the extrapolation of the X-ray spectrum, suggesting at least two regions contributing to the synchrotron flux. Finally we investigate a gamma-ray flare not accompanied by an X-ray counterpart. This peculiar outburst is interpreted using a time-dependent model involving two emitting components.
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Arbet Engels, A, Mondal, H A, Fukami, S, D’Ammando, F, Dorner, D, Chatterjee, R, Majumdar, P, Manganaro, M, Hovatta, T, Das, S, Raiteri, C M, Villata, M, Perri, M, Verrechia, F, Leto, C, Filippenko, A, Zheng, W & MAGIC Collaboration 2024, 'Long-term study of the intermittent extreme behaviour of 1ES 2344+514', POS Proceedings of Science, vol. 444, 788. https://doi.org/10.22323/1.444.0788