Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES 2344+514
Articolo
Data di Pubblicazione:
2024
Abstract:
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 νsynch;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.Morethan 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 νsynch;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 νsynch;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.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
BL Lacertae objects: individual: 1ES 2344+514; galaxies: active; radiation mechanisms: non-thermal
Elenco autori:
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.; Babic A.; Baquero A.; Barres De Almeida U.; Batkovic I.; Baxter J.; Becerra Gonzalez J.; Bernardini E.; Bernete J.; Berti A.; Besenrieder J.; Bigongiari C.; Biland A.; Blanch O.; Bonnoli G.; Bosnjak Z.; 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.; Farina L.; Fattorini A.; Foffano L.; Font L.; Fukami S.; Fukazawa Y.; Garcia Lopez 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.; Hutten M.; Imazawa R.; Inada T.; Iotov R.; Ishio K.; Jimenez Martinez I.; Jormanainen J.; Kerszberg D.; Kluge G.W.; Kobayashi Y.; Kouch P.M.; Kubo H.; Kushida J.; Lainez Lezaun M.; Lamastra A.; Leone F.; Lindfors E.; Linhoff L.; Lombardi S.; Longo F.; Lopez-Moya M.; Lopez-Oramas A.; Loporchio S.; Lorini A.; MacHado De Oliveira Fraga B.; Majumdar P.; Makariev M.; Maneva G.; Mang N.; Manganaro M.; Mariotti M.; Martinez M.; Martinez-Chicharro M.; Mas-Aguilar A.; Mazin D.; Menchiari S.; Mender S.; Miceli D.; Miener T.; Miranda J.M.; Mirzoyan R.; Molero Gonzalez M.; Molina E.; Mondal H.A.; Moralejo A.; Morcuende D.; Nakamori T.; Nanci C.; Neustroev V.; Nigro C.; Nikolic 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.; Pavlovic D.; Persic M.; Pihet M.; Pirola G.; Podobnik F.; Prada Moroni P.G.; Prandini E.; Principe G.; Priyadarshi C.; Rhode W.; Ribo 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.; Striskovic J.; Strom D.; Suda Y.; Tajima H.; Takeishi R.; Tavecchio F.; Temnikov P.; Terauchi K.; Terzic 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.; 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.
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