Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES 2344+514

DOI: 
10.1051/0004-6361/202347845
Publication date: 
11/02/2024
Main author: 
MAGIC Collaboration
IAA authors: 
Agudo, I.;Castro-Tirado, A. J.;Escudero, J.;Multi-wavelength Collaborators
Authors: 
MAGIC Collaboration;Abe, H.;Abe, S.;Acciari, V. A.;Agudo, I.;Aniello, T.;Ansoldi, S.;Antonelli, L. A.;Arbet Engels, A.;Arcaro, C.;Artero, M.;Asano, K.;Baack, D.;Babić, A.;Baquero, A.;Barres de Almeida, U.;Batković, I.;Baxter, J.;Becerra González, J.;Bernardini, E.;Bernete, J.;Berti, A.;Besenrieder, J.;Bigongiari, C.;Biland, A.;Blanch, O.;Bonnoli, G.;Bošnjak, Ž.;Burelli, I.;Busetto, G.;Campoy-Ordaz, A.;Carosi, A.;Carosi, R.;Carretero-Castrillo, M.;Castro-Tirado, A. J.;Chai, Y.;Cifuentes, A.;Cikota, S.;Colombo, E.;Contreras, J. L.;Cortina, J.;Covino, S.;D'Amico, G.;D'Ammando, F.;D'Elia, V.;Da Vela, P.;Dazzi, F.;De Angelis, A.;De Lotto, B.;Del Popolo, A.;Delfino, M.;Delgado, J.;Delgado Mendez, C.;Depaoli, D.;Di Pierro, F.;Di Venere, L.;Dominis Prester, D.;Dorner, D.;Doro, M.;Elsaesser, D.;Emery, G.;Escudero, J.;Fariña, L.;Fattorini, A.;Foffano, L.;Font, L.;Fukami, S.;Fukazawa, Y.;García López, R. J.;Gasparyan, S.;Gaug, M.;Giesbrecht Paiva, J. G.;Giglietto, N.;Giordano, F.;Gliwny, P.;Grau, R.;Green, J. G.;Hadasch, D.;Hahn, A.;Heckmann, L.;Herrera, J.;Hrupec, D.;Hütten, M.;Imazawa, R.;Inada, T.;Iotov, R.;Ishio, K.;Jiménez Martínez, I.;Jormanainen, J.;Kerszberg, D.;Kluge, G. W.;Kobayashi, Y.;Kouch, P. M.;Kubo, H.;Kushida, J.;Láinez Lezáun, M.;Lamastra, A.;Leone, F.;Lindfors, E.;Linhoff, L.;Lombardi, S.;Longo, F.;López-Moya, M.;López-Oramas, A.;Loporchio, S.;Lorini, A.;Machado de Oliveira Fraga, B.;Majumdar, P.;Makariev, M.;Maneva, G.;Mang, N.;Manganaro, M.;Mariotti, M.;Martínez, M.;Martínez-Chicharro, M.;Mas-Aguilar, A.;Mazin, D.;Menchiari, S.;Mender, S.;Miceli, D.;Miener, T.;Miranda, J. M.;Mirzoyan, R.;Molero González, M.;Molina, E.;Mondal, H. A.;Moralejo, A.;Morcuende, D.;Nakamori, T.;Nanci, C.;Neustroev, V.;Nigro, C.;Nikolić, L.;Nishijima, K.;Njoh Ekoume, T.;Noda, K.;Nozaki, S.;Ohtani, Y.;Okumura, A.;Otero-Santos, J.;Paiano, S.;Palatiello, M.;Paneque, D.;Paoletti, R.;Paredes, J. M.;Pavlović, D.;Persic, M.;Pihet, M.;Pirola, G.;Podobnik, F.;Prada Moroni, P. G.;Prandini, E.;Principe, G.;Priyadarshi, C.;Rhode, W.;Ribó, M.;Rico, J.;Righi, C.;Sahakyan, N.;Saito, T.;Satalecka, K.;Saturni, F. G.;Schleicher, B.;Schmidt, K.;Schmuckermaier, F.;Schubert, J. L.;Schweizer, T.;Sciaccaluga, A.;Sitarek, J.;Spolon, A.;Stamerra, A.;Strišković, J.;Strom, D.;Suda, Y.;Tajima, H.;Takeishi, R.;Tavecchio, F.;Temnikov, P.;Terauchi, K.;Terzić, T.;Teshima, M.;Tosti, L.;Truzzi, S.;Tutone, A.;Ubach, S.;van Scherpenberg, J.;Ventura, S.;Verguilov, V.;Viale, I.;Vigorito, C. F.;Vitale, V.;Walter, R.;Wunderlich, C.;Yamamoto, T.;Multi-wavelength Collaborators;Perri, M.;Verrecchia, F.;Leto, C.;Das, S.;Chatterjee, R.;Raiteri, C. M.;Villata, M.;Semkov, E.;Ibryamov, S.;Bachev, R.;Strigachev, A.;Damljanovic, G.;Vince, O.;Jovanovic, M. D.;Stojanovic, M.;Larionov, V. M.;Grishina, T. S.;Kopatskaya, E. N.;Larionova, E. G.;Morozova, D. A.;Savchenko, S. S.;Troitskiy, I. S.;Troitskaya, Y. V.;Vasilyev, A. A.;Chen, W. P.;Hou, W. J.;Lin, C. S.;Tsai, A.;Jorstad, S. G.;Weaver, Z. R.;Acosta-Pulido, J. A.;Carnerero, M. I.;Carosati, D.;Kurtanidze, S. O.;Kurtanidze, O. M.;Jordan, B.;Ivanidze, R. Z.;Gazeas, K.;Vrontaki, K.;Hovatta, T.;Liodakis, I.;Readhead, A. C. S.;Kiehlmann, S.;Zheng, W.;Filippenko, A. V.;Fallah Ramazani, V.
Journal: 
Astronomy and Astrophysics
Publication type: 
Article
Volume: 
682
Pages: 
A114
Abstract: 
<BR /> Aims: The BL Lac 1ES 2344+514 is known for temporary extreme properties characterised by a shift of the synchrotron spectral energy distribution (SED) peak energy ν<SUB>synch, p</SUB> above 1 keV. While those extreme states have only been observed during high flux levels thus far, additional multi-year observing campaigns are required to achieve a coherent picture. Here, we report the longest investigation of the source from radio to very high energy (VHE) performed so far, focussing on a systematic characterisation of the intermittent extreme states. <BR /> Methods: We organised a monitoring campaign covering a 3-year period from 2019 to 2021. More than ten instruments participated in the observations in order to cover the emission from radio to VHE. In particular, sensitive X-ray measurements by XMM-Newton, NuSTAR, and AstroSat took place simultaneously with multi-hour MAGIC observations, providing an unprecedented constraint of the two SED components for this blazar. <BR /> Results: While our results confirm that 1ES 2344+514 typically exhibits ν<SUB>synch, p</SUB> &gt; 1 keV during elevated flux periods, we also find periods where the extreme state coincides with low flux activity. A strong spectral variability thus happens in the quiescent state, and is likely caused by an increase in the electron acceleration efficiency without a change in the electron injection luminosity. On the other hand, we also report a strong X-ray flare (among the brightest for 1ES 2344+514) without a significant shift of ν<SUB>synch, p</SUB>. During this particular flare, the X-ray spectrum is among the softest of the campaign. It unveils complexity in the spectral evolution, where the common harder-when-brighter trend observed in BL Lacs is violated. By combining Swift-XRT and Swift-UVOT measurements during a low and hard X-ray state, we find an excess of the UV flux with respect to an extrapolation of the X-ray spectrum to lower energies. This UV excess implies that at least two regions significantly contribute to the infrared/optical/ultraviolet/X-ray emission. Using the simultaneous MAGIC, XMM-Newton, NuSTAR, and AstroSat observations, we argue that a region possibly associated with the 10 GHz radio core may explain such an excess. Finally, we investigate a VHE flare, showing an absence of simultaneous variability in the 0.3−2 keV band. Using time-dependent leptonic modelling, we show that this behaviour, in contradiction to single-zone scenarios, can instead be explained by a two-component model.
Database: 
ADS
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2024A&A...682A.114M/abstract
ADS Bibcode: 
2024A&A...682A.114M
Keywords: 
radiation mechanisms: non-thermal;galaxies: active;BL Lacertae objects: individual: 1ES 2344+514;Astrophysics - High Energy Astrophysical Phenomena