Details

Autor(en) / Beteiligte

• Ansoldi, S.
• Antonelli, L. A.
• Arcaro, C.
• Asano, K.
• Babić, A.
• Becerra González, J.
• Bernardini, E.
• Bigongiari, C.
• Blanch, O.
• Bonnoli, G.
• Busetto, G.
• Carretero-Castrillo, M.
• Cikota, S.
• Contreras, J. L.
• D’Ammando, F.
• Da Vela, P.
• De Lotto, B.
• Del Popolo, A.
• Delgado Mendez, C.
• Di Pierro, F.
• Dominis Prester, D.
• Dorner, D.
• Font, L.
• Fukazawa, Y.
• Giordano, F.
• Grau, R.
• Green, J. G.
• Hadasch, D.
• Hütten, M.
• Jiménez Martínez, I.
• Jormanainen, J.
• Kerszberg, D.
• Kluge, G. W.
• Kouch, P. M.
• Kubo, H.
• Lamastra, A.
• Leone, F.
• Linhoff, L.
• Lombardi, S.
• Longo, F.
• López-Moya, M.
• Loporchio, S.
• Mang, N.
• Manganaro, M.
• Martínez-Chicharro, M.
• Mas-Aguilar, A.
• Menchiari, S.
• Mender, S.
• Morcuende, D.
• Nakamori, T.
• Nikolić, L.
• Noda, K.
• Okumura, A.
• Otero-Santos, J.
• Palatiello, M.
• Paneque, D.
• Paredes, J. M.
• Persic, M.
• Pihet, M.
• Prandini, E.
• Rhode, W.
• Righi, C.
• Saito, T.
• Stamerra, A.
• Strom, D.
• Suda, Y.
• Tajima, H.
• Tavecchio, F.
• Terzić, T.
• Tosti, L.
• Ventura, S.
• Verguilov, V.
• Viale, I.
• Vitale, V.
• Wunderlich, C.
• Perri, M.
• Leto, C.
• Raiteri, C. M.
• Villata, M.
• Ibryamov, S.
• Bachev, R.
• Strigachev, A.
• Jovanovic, M. D.
• Stojanovic, M.
• Kopatskaya, E. N.
• Morozova, D. A.
• Savchenko, S. S.
• Troitskiy, I. S.
• Chen, W. P.
• Lin, C. S.
• Weaver, Z. R.
• Acosta-Pulido, J. A.
• Carnerero, M. I.
• Carosati, D.
• Kurtanidze, S. O.
• Jordan, B.
• Gazeas, K.
• Hovatta, T.
• Readhead, A. C. S.
• Zheng, W.

Titel

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

Ist Teil von

• Astronomy and astrophysics (Berlin), 2024-02, Vol.682, p.A114

Ort / Verlag

Heidelberg: EDP Sciences

Erscheinungsjahr

2024

Quelle

EZB Free E-Journals

Beschreibungen/Notizen

• 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 synch, p 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. 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. Results. While our results confirm that 1ES 2344+514 typically exhibits ν synch, p  > 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 synch, p . 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.