The BL Lac type object 1ES 2344+51.4 (redshift z = 0.044) was one of the first sources to be included in the extreme high-peaked BL Lac (EHBL) family. EHBLs are characterised by a broadband spectral energy distribution (SED) featuring the synchrotron peak above ∼ 1017 Hz. From previous studies of 1ES 2344+51.4 in the very-high-energy (VHE, >100 GeV) gamma-ray range, its inverse Compton (IC) peak is expected around 200 GeV. 1ES 2344+51.4 was first detected in the VHE range by Whipple in 1995 during a very bright outburst showing around 60% of the flux of the Crab Nebula above 350 GeV. In 1996, during another flare in the X-ray band, observations with Beppo-SAX revealed a large 0.1-10 keV flux variability on timescales of a few hours and an impressive frequency shift of the synchrotron peak to above 1018 Hz. Later on, this extreme behaviour of the source motivated several multiwavelength campaigns, during most of which the source appeared to be in a low state and showing no clear signs of “extremeness”. In August 2016, FACT detected 1ES 2344+51.4 in a high state and triggered multiwavelength observations. The VHE observations show a flux level similar to the historical maximum of 1995. The combination of MAGIC, FACT, and Fermi-LAT spectra provides an unprecedented characterisation of the IC peak. It is the first time that simultaneous HE and VHE data are presented for this object during a flaring episode. We find an atypically hard spectrum in the VHE γ-rays as well as a hard X-ray spectrum, revealing a renewed extreme behaviour.
Axel Arbet-Engels, M. Manganaro, M. Cerruti, V. Fallah Ramazanı, D. Dorner, Vitalii Sliusar, Alexei V Filippenko, T. Hovatta, V. M. Larionov, J. A. Acosta‐Pulido, C. M. Raiteri, WeiKang Zheng
M. Manganaro, M. Seglar-Arroyo, J. Becerra González, D. A. Sanchez⋆, M. Cerruti, F. Tavecchio, Vandad Fallah-Ramazani, I. Agudo, S. Ciprini, Alexei V Filippenko, A. Esteban-Gutiérrez, T. Hovatta, Helen Jermak, S. G. Jorstad, E. N. Kopatskaya, V. M. Larionov, V. M. Larionov, Anne Lähteenmäki, Alan P. Marscher, D. A. Morozova, Marko Pahljina, M. Tornikoski, Yuliya Troitskaya, I. S. Troitsky, F. Verrecchia, Hubing Xiao, Z. R. Weaver, WeiKang Zheng, V. A. Acciari, Stefano Ansoldi, L. A. Antonelli, A. Arbet Engels, Manuel Artero,
A. Furniss, D. A. Williams, Charles Danforth, Michele Fumagalli, J. X. Prochaska, Joel R. Primack, C. M. Urry, John T. Stocke, Alexei V Filippenko, William Neely
T. J.-L. Courvoisier, A. Blécha, P. Bouchet, P. Bratschi, M. T. Carini, Megan Donahue, Rick Edelson, Eric D. Feigelson, Alexei V Filippenko, I. S. Glass, J. Heidt, R. I. Kollgaard, T. Matheson, H. R. Miller, J. C. Noble, K. Sekiguchi, Paul S. Smith, C. M. Urry, S. J. Wagner
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